I switched from an HTC One M8 (before that, S4). I was hesitant to go to a Motorola, but they really did a nice job of leaving stock android alone and only adding some items, such as moto voice, assist, etc...which are actually all very useful. HTC and Samsung add stuff and I never used it.
This phone is phenomenal and the big knocks against it (at least what I read about it) were the speakers and that it is ugly and neither of which bother me in any way. The ballistic nylon is really unique and the form factor is...about the same as every other phone. Speakers, no issues so far, must be a lot of hearing impaired folks testing the phone out.