Since 2014 we have a lot of devices which are affordable, yet capable enough to give the flagship phones a run for their money. ASUS is one of the player you simply couldn’t ignore in the so-called flagship killers with the introduction of their ZenFone 2. While the low price is one of the attractions, being the first phone to carry 4GB of RAM allows the ZenFone to steal a fair share of spotlight from other devices launched earlier this year. It has been months since the ZenFone 2 was launched but is it still good enough? Well, we are here to answer that question.


There are a few phones which carry the “ZenFone 2” name to we would like to clarify that the unit we are reviewing is the ASUS ZenFone 2 ZE551ML, which packs 32GB of internal storage and 4GB of RAM. There are a lot of variants of ZenFone 2 out there with different processors, display and memory size. I really think that the weird naming scheme will bring a lot of confusions to average consumers and I still don’t get the reason behind it.


The box carrying the ASUS ZenFone 2 has the same colour with the phone printed on top of the white background. So, red box for our red unit. I guess that will be easier for resellers to find the correct unit for their customers?


You will see the phone covered with plastic wrappings for protection once you pull out the box. Underneath the phone you will find the usual accessories: a pair of earphones, an USB cable, a charging adapter and some documents.


The pair of earphones provided sounds pretty ordinary to me, but I like the fact that the cables are flat so it won’t get tangled as easily. The charging adaptor, on the other hand, really packs a punch. It supports 9V/2A fast charging to reduce charging time on the ZenFone 2 (more on that later). Of course, it will toggle the output to 5V/2A if it detects that the other devices you connect does not support that amount of voltage. In other words, you don’t need to worry about damaging your devices with this powerful charger.


For a lot of affordable flagship phones, the manufacturers will sacrifice the look to pack in better components so that the specifications list looks more appealing. This kind of tradeoff is acceptable by most people but ASUS seems to think differently. If you inspect the ZenFone 2 closely, it is not hard to see that ASUS has put in a lot of effort in the design. We have a red unit and I have to say I really like the colour a lot. It is a little unconventional and it is perfect for those who are little tired of the boring black and white designs. On the other hand, it is not extremely striking to catch everyone’s attention once you pull your phone out of your pocket.


The back of the phone has a metallic hairline finish which gives the phone a premium look even though it is only made of plastic. The back of the phone is curved. The middle of the phone is the thickest with a thickness of 10.9mm while the both sides is only 3.9mm thick. This arc design is certainly great for ergonomics as the curved back rest nicely in your hand and the thin sides will hide the truth that the phone is actually quite thick. The only downside I can think of is that the phone will wobble if you try to use it on the table. Maybe ASUS thinks that the phone should stay in your hand rather than sitting on the table? 


Looking at the front you will see the display taking up most of the space. The bezels of the ZenFone 2 is thinner as compared to its predecessor, bringing the screen–to-body ratio to 72%. The number is not outstanding if you compared to other flagships, but no doubt it is a great improvement. The trademark concentric circle at the chin of the phone was inherited from the first generation of ZenFones below the hardware capacitive keys. With the circular metallic surface, some part will reflect the light while the other part will be darker and the look will change depending on the direction of the light source. This gives the phones an interesting look.


The same concentric circle design can be found on all the buttons too. The buttons are silver in colour and the “circles” here have slightly larger gaps between them. As a result, the concentric circle design is even more pronounced here. Speaking of the buttons, ASUS has placed them in slightly unconventional positions. The volume rocker is placed at the back, below the rear camera. You will take some time to get used to the positions of the volume buttons, but after that you will realize that this design make sense for phablets as it is easier to reach. However, you can’t change the volume without picking the phone up (It really seems that the phone wants to be in your hand all the time).


This design is very similar with LG’s phones, except the fact that the ZenFone 2’s power button is located on the very top of the phone instead of sitting between the volume up and volume down button. The power button is extremely hard to reach. ASUS certainly noticed that too so they allow you to double tap on the locked screen to wake the phone and you can double tap on the empty space of the home screen to turn the display off. To make things simpler, make sure you don’t fill up every page of your home screen with widgets and icons since the double tap to sleep only work on empty space. With this feature, I almost forget the existence of the power button on top and I didn’t find it very annoying.


The back of the phone is removable so it is possible to swap covers if you find your old one boring or damaged. However, the 3,000mAh battery under the hood is not removable although you can see it once your removed the back. Please don’t try to pry it open. You also have access to the slots for 2 SIM cards and microSD card after the back cover is removed.


I think ASUS has done a good job in the design of the ZenFone 2. The other phones with similar price does not seem to have as much attention from their creators in their designs. It looks great and the feel in hand is really amazing. Like other ASUS devices, the build quality is very convincing. That being say, it is still hard to believe that you can find such premium design with affordable flagships like this. I think design of the ZenFone 2 really stands out of the crowd, even months after it was launched.


ASUS ZenFone 2 has a 5.5” IPS LCD display with a resolution of 1920×1080. While “true” flagships like Samsung Galaxy S6 have Quad HD display, I didn’t expect the ZenFone 2 to come with one given that it costs only half the price at launch. Moreover, I still think that Full HD will be sufficient for a smartphone and with the pixel density of 401 ppi here, I am happy with the resolution.


For me, the colour accuracy of the display matters more than the amount of pixels. Fortunately, the colour of the display is natural and quite accurate. White is white and black is quite dark for a LCD display. If you are unhappy with the colours out of the box, ASUS lets you to have the freedom to customize it via its Splendid software. You can select between balance mode, bluelight filter (which makes your display super yellowish but easier for your eyes), vivid or you can customize the hue, saturation and temperature according to your taste. I think this will be useful as it is hard to please everyone. However, personally I feel that the default setting is good enough for me.


The ASUS devices we reviewed previously have a common problem: the display glass is too reflective, resulting in limited viewing angle. The improvement is obvious here on the ZenFone 2. The viewing angle is better and I feel that reading the screen is easier when I am sitting beside my window. The only problem I have with the display is the brightness. The screen is not bright enough to be read easily under sunlight, even If you max out the brightness manually. It is not totally unreadable, but there are a lot of brighter display out there. So if you tend to use your phone outdoors, you might have to seek for other options. For the rest of us, the brightness of the display is adequate and the auto-brightness works fine in both well-lit and dark places.

So other than the limited brightness, I think that the display is good enough. There is still a gap for the display between the ZenFone 2 and the best phones out there, but I think it will be good enough for most people. Factoring in the price, I don’t think anyone should complain. Considering all the phones with similar price, I think the ZenFone 2 has one of the best displays.


The performance is certainly a main story for this review as the ZenFone 2 is the world’s first phone to carry a whopping 4GB of RAM. The processor that comes along with the 4GB of RAM is Intel Atom Z3580, which has 4 cores clocked at 2.3GHz. So how well does the combination fair? Well, it’s a mixed story.

The Intel Atom Z3580 processor is quite a fast performer. Even though it is obviously not as fast as the top players like Qualcomm’s Snapdragon 810 and Samsung’s Exynos 7420, it is not really far behind on basic usage. The apps won’t open as fast but after the app is loaded, you can hardly notice any lag even on the most graphic intense games you can play on Android phones. Navigation through user interface, watching high definition videos and other normal tasks can be done without any hiccup.

So what kind of role does the 4GB of RAM plays here? The RAM in your phone allows more apps to stay at background while not being killed. When the apps are not killed by the system, it can be resumed when you try to use the app again. We tend to use the same apps over and over again,  so without having to load them again and again will save you quite some time in a long run.  So naturally with more RAM on board, your apps are less likely to be closed and the apps need not to be loaded all over again. The processor on the ZenFone 2 may not be the fastest, but the 4GB of RAM allows the apps to be resumed and resuming apps will take less than time than loading up the applications again. This is the part where the ZenFone 2 excels as compared to other flagships.


As you can imagine, you also can hop between few apps since these apps can “live” simultaneously. This results in great multitasking experience. It amazes me every time that the game I played last night can be resumed immediately. If you want to try something extreme, you can actually jump between few games like Asphalt 8, NOVA 3 and Injustice without letting the system to kill anyone of them. Of course, you must not kill all the background apps manually to see the effect. With that amount of RAM, you can trust the software to take care of the background task for you.

While it seems easy for any manufacturers to pack in extra RAM to achieve the stated benefits, it is actually not that simple. The software must be efficient to make the extra RAM worthy and I am glad to say that ASUS did a great job in their software optimization. The effect of the extra RAM might not be as straight-forward and you might not notice it if you are not aware of it. However, I can clearly feel the difference of having 4GB of RAM over here. It is more to a nice-to-have feature rather than a must-have feature but I am convinced that the 4GB of RAM is more than a marketing gimmick.

Battery Life

The first generation’s ZenFone suffered from limited badly from limited battery life and ASUS wants to change that by packing a 3,000mAh battery into the ZenFone 2. However, I still will not say that the battery life is great. On a normal day with some messaging, browsing the social media, surfing the web and playing some games, the phone can last around 14 hours with around 3.5 hours of screen-on time. So the battery can carry me for just a single day at most. If I game a lot that day, I usually have to top up the charge in the evening. Take note that I am using Balanced mode in the battery modes. I have tried using Performance mode. Even though the phone seems to be snappier, you can expect the screen-on time to be reduced by 30 minutes.


The battery life is not really convincing if you consider that the phone actually has quite a huge battery. I have no idea this is caused by the inefficiency of processor or the software. The fact that the battery is not removable is not helping too. Luckily, the ZenFone 2 supports fast charging, as mentioned earlier. With 10 minutes of charging time, you will get around 15% of the charge and 40% can be reached within half an hour. By the one-hour mark, you should have 75% of the charge already. I couldn’t count how many times have the fast-charging bailing me out of trouble and I really like this feature. Take note that the phone will get quite warm during fast charging, as indicated by the warning on the screen.

power options

So the bottom line here is that the battery can last for a day if you are not a heavy user. If the phone runs out of the juice, at least you know you can rely of the fast-charging. So it wasn’t that bad after all.


In terms of storage, ZenFone 2 comes with either 32GB, 64GB or 128 GB of storage. I like the fact that we have the choice to choose whatever size we need. For the 32GB model, you will have aroudn25GB free out of the box. Furthermore, there is a microSD card slot to expand your storage. Therefore, storage should not a problem at all.


The ZenFone 2 can also support 2 SIM cards simultaneously. I have no problem getting cellular signals at all. LTE data connection, on top of other connectivity options such as WiFi 802.11 a/b/g/n/ac and Bluetooth 4.0, are present. ZenFone 2 also has NFC, unlike a lot of other budget phones.


The row of speaker grills at the back of the phone would suggest that the speaker might carry some “oomph”, but sadly that isn’t the case. If you remove the back cover, you would realize that the speaker is placed on one side. More importantly, the volume is a little lacking. When you consider that the speaker is placed at the back and it is so soft, the audio experience is not really great. I have trouble listening to it at public places if I didn’t have my earphones with me. The placement, volume and quality of the speaker is definitely not ideal. So if you care about audio quality, chances are you will be disappointed here.


ASUS has been doing some hard work on the software side. ZenFone 2 is running ZenUI on top of Android 5.0 Lollipop, which is not the latest version of the mobile operating system. The reason why Android 5.1 is not pushed out yet is unknown and ASUS really need to step up their game on delivering updates as a lot of their devices are stuck at older version of Android. Thankfully, ASUS is still providing software updates from time to time to deliver security patches and squashing bugs. Most of the system applications are placed on the Google PlayStore and this allows ASUS to update them individually without the need of frequent full-system updates.


ASUS has blended their ZenUI elements with the Lollipop interface quite well. The drop-down notification shade and quick-toggle setting page looks cohesive with the rest of the user interface. One big improvement found on ZenUI is the theme support. You can basically change any part of the interface, including icons, fonts, transition and others with any theme you like. You can also mix and match the elements from different themes.


Aesthetics aside, ASUS also implemented a few useful features. You can draw different gestures on the locked screen to launch application according to your own customisation. For example, you can draw a “C” to launch the calculator application. There is also a one-handed mode which can be activated by double tapping the home button. The screen will be shrunk to one corner for easier access. There are kids/guest mode for you to share your phone without worrying people to mess up with your stuffs. Easy mode is also available for people who think that the typical Android interface is too challenging.

easy mode

kids mode

One complaint I have with the ZenFone 2 is that there are way too many applications that come out of the box and not all of them are useful, at least for me. Applications like JawBone Up, ZenCircle, Zinio, Amazon Kindle, Dr. Safety and others are not must-have and having so many bloatwares coming out of the box is not a great experience. I kind of feel like someone has messed up my phone and I definitely don’t want to see this when I just start using my phones. Even though most of them can be removed later, I hope that ASUS will cut this down in future devices.


It is undeniable that ASUS has put in a lot of effort on the software of the ZenFone 2. But they have to realize that not all of their work might be appreciated and finding balance between offering useful features or extra bloatware can be really difficult. Since the new trend is to make the software lighter, ASUS might need to change their direction a little bit.


ASUS ZenFone 2 has a 13MP camera at its rear. The resolution is definitely sufficient for most people, but what matter the most is the picture quality. Luckily, the quality of the photos can match the competition among the phones within its price bracket. Most of the time the photo taken are quite nice, even in auto mode. The colours are sufficiently rich. The shallow depth of field during macro shots also make photo more interesting.






However, sometimes the camera will be slightly over-exposed if there are strong light coming in the photos. The dynamic range is certainly limited as compared to flagship phones like the Samsung Galaxy S6. Thus I think that HDR mode is really important for the ZenFone 2 as it helps me to get quite a number of nice photos.


Low light photography is a little tricky here. Most of the time with auto or night mode you can get acceptable photos, albeit a little dark. But if you want to have bright up the photos in the dark, you can use the Low Light mode, which will give you significantly brighter photos but at the cost of noise addition and smaller resolution. I didn’t use this mode very often as it will make the exposure time extremely long and your hands need to be very steady to avoid blurred image.



ASUS did placed in some software features to make the photography experience nicer. For example, Super Resolution mode will stitch 4 photos together to give you a 52 megapixel photo. This mode will give you a little more details, but the file size grows proportionally too. The 5MP front facing camera is neither fascinating nor depressing to use. The beautification mode allows you to touch up your selfies easily. One thing I like is that you can pull up the shuttle button to set a timer, instead of digging through the settings. This is really thoughtful.

In short, the photos are quite good if you are comparing phones with the same price. The ZenFone 2 is dwarfed by the other flagship phones. But if you consider the price difference, I don’t think anyone should have much complaint. Here are some sample photos for your reference:

The Good

  • Affordable Price
  • Nice and comfortable design
  • Solid and smooth performance
  • A lot storage options and microSD card supported

The Bad

  • Too many bloatwares
  • Slow Android upgrade
  • Weak speaker
  • Dim display


The ZenFone 2 is really an all-rounded phone. To be honest, I didn’t have much to complaint. As I not really an outgoing person, the weak speaker and dimmer display are not really a big trouble for me. It required my one-time effort to clean up the bloatwares, after that I am good to go. Not getting Android upgrades is something pretty common in the market, although it is not a nice thing to see. So that is why I like the ZenFone 2 so much.


In return, I got phone which works for me really well. The phone is quite smooth and with that much amount of RAM, I don’t really need to manage the background applications. The battery can mostly last me a day and fast charging is always there for me if the phone ran out of juice. The camera works okay for me if I didn’t bring my camera for me and the display is pleasant to see if you are not looking it under the sun. So mostly, the good has outdid the bad parts.


More importantly, the ASUS ZenFone 2 is really affordable. The 32GB model comes at only RM1099 and the 64GB and 128GB models comes at RM1199 and RM1599 respectively. With our dear Ringgit going weak, the other new phones are getting more expensive in Malaysia. Therefore, I am willing to recommend this phone to anyone who wants a phone that works well and don’t need to micro-manage it. Power-users might still find it a little lacking, but the ZenFone 2 is definitely much, much better than the first generation of ZenFones.

So here’s it. The ZenFone 2 will be a right choice for a lot of people even though it has been on the market for a long time. It is great to see smaller players like ASUS improving so much. I couldn’t wait to see what will they offer in the next generation of ZenFone.