I've been going back and forth on picking up HOMM3 since it came out on iOS... By all accounts that I've read it's a solid offering except for some gripes about the UI. It doesn't and won't have either of the two expansions but apparently you can load maps to it using iTunes. I don't know if it supports 64-bit though.
I'm gonna stick to my GOG copy for now but you should report back if you buy it :D.
Did not hear good things on the "HD Port". It is way better to use the HD Mod instead of buying this version apparently though this does not apply to the iOS version f course.
Given the last update's release date it must be 64Bit.
Played it a bit this morning and it seems fine to me. The game mechanics are a little obscure to me at the moment because I only ever really played a tiny bit of HOMM5, the tutorial doesn't really go any deeper then controls, and it's of an older generation of games.
But I think it controls fine, looks fine, I'm looking forward to playing more of it because I've heard good things about this entry.