I was excited with the specs of Asus Zenfone 2 when I first heard about it..and then was eagerly waiting for it to be on my palm. The specs, cost and the Red color attracted me most. So here is my feedback after using both the 2GB(16GB) and 4GB(32GB) ZE551ML versions.
Let's start with few critical points-
1. RAM - For 2GB RAM version, even after uninstalling all bloatwares possible and disabling all apps through Auto-start Manager, you end up having 600-700MB RAM most of the times. Sometimes, it gets down to 300-400MB too. Restarting the phone gets it up back to 800MB though. Even in 4GB RAM, most of the times you would get mostly around 2.2-2.3GB RAM. So, gist is, ZenUI packed OS eats up considerable RAM space, which is why I had to switch from 2GB to 4GB. Just to compare, my earlier phone Sony Xperia ZR with 2GB RAM, at any moment had more than 1GB RAM free, which was really great! Overall, I haven't seen any lagging while using in the 4GB versions, though a little bit on 2GB versions, but thats pretty marginal and for few seconds only.
2. Battery - 3000Mh sounds pretty heavy, however it doesn't perform up to the expectations though. With wifi on and 30 mins of gaming/streaming, the batter % goes down 1% almost every minute. So, if you start with 100%, after 30 minutes of heavy usage you'll end up with battery strength at close to 70%. But, in sleep mode, it stays pretty well. Also, with Asus boost charging available with 4GB versions, it really helps to have the phone fully charged within 80-90 minutes.
3. Display - Just about okay, works fine with me though didn't find it as gorgeous as my Sony Xperia ZR. Somehow, I feel display isn't bad for sure but could have been a bit better, overall with Full HD view.
4. Camera - I am not an expert, but this one is good enough for me with lots of betterment and customization modes, probably better than my Sony Xperia ZR (surprisingly, yes!). But, there are people who might not have been satisfied with the camera, so it comes down to individual opinions, which may differ.
5. Design and Look - The Red one looks really awesome and attractive! The design is pretty good too, ensuring I feel comfortable holding a 5.5inch screen on my comparatively smaller hands. Perhaps, I would have liked the regular positions of the volume control and screen lock buttons at the side instead of back and top respectively.
6. Speakers - Just about fine with it so far though could have been a bit louder. Speakers inside is actually smaller than the outlet shows on the back. Surprisingly, Bass boosting and Surround sound is available only in earphone/headphone mode, thats a negative in my book.
7. Sim - Though it's a Dual Sim phone, the second Sim slot will work only in 2G mode and can't connect to Internet. So, disappointed with it.
8. Flipkart - In case you have bought any phone and willing to return/exchange for any reason within 30 days, I suppose you won't get it. Because, for Flipkart it has to be a techincal fault to agree to return/replace it just being overall unsatisfied isn't enough. Though the delivery service is as usual great, but the after sales service is degrading day-by-day. So, guys, think again if you want to replace in particular costly mobile phones.
As far as the phone is concerned, this is absolute beauty of a phone with great specs, price, design, looks and charger with few 'just-short-of-expectations' observations. Definitely, I would recommend everyone to consider this one particularly for daily-users willing to have a high specs yet cost saving phone.