Great phone, but not perfect.
Its very fast and responsive, although it was a fairly short battery life, I would say I am a moderate user, and I am needing to charge it every night.
But it can run anything, and can run anything quickly.
The volume key placement is slightly awkward, but isn't too bad compared to the placement of the lock button which I never have to use anyway because you can wake the phone by double tapping the screen, which is SO HELPFUL.
Plus the ZenUI is great, you can change the look of almost every aspect of the Android OS.
Online reviews say the speaker is weak, but I think its fine, if you want to play music on your phone you should be using headphones anyway.
The ZenFone 2 is very enjoyable, and gives a high end experience with a mid range price.