Great device to use. Using it personally with no problem.
Miui is great running in this mobile and the custom rom also.
Used miui 5 & 6 and also cm11, cm12 and now running the latest cm12.1.
Those who think that rooting and flashing custom rom will void warranty. Then I must say that it NO. You can flash new custom rom to this device without any problem.
Using now crdroid based on cm12.1 in this device.