I had to do a hard factory reset with it after updating the HTC Sense package and lock screen,Home,Dot view...Was getting the constant Gapps failed with it
I haven't updated any of them and have been enjoying the best battery life ever on this phone.
Very smooth and no issues cept for lag on the messaging application. Once I deleted some old ones from last year everything was good. I like Lollipop on AT&T M8.