I've owned every version of Apple TV (including the clunky 1st gen). Love the 4. I think my favorite things so far are:
- The new remote (totally did not expect to like it)
- The UI is fast
- The apple tv controls my TV without me setting anything up
- My TV remote (Sony) controls the Apple TV without me setting anything up
- 802.11AC wifi
BTW I don't know if you guys noticed but every TV app supports Comcast now (at least all the ones I downloaded).