Finally got it delivered, played for 4 hours or so.
While the potential for awesomeness is there, (i.e. more in-depth rewards from respect/cash), the city feels pretty damn empty. I miss Fuzz and Crowd Control :/
The story missions that don't turn into side missions are amazing, but once you've done the side missions a few times, I dunno, it's just not clicking for me yet like SR2 did. (Disclaimer: things very well may change as I get further in)
The improvements in SR3 are great, but if they could, say, combine SR3's levelling/respect system with SR2's larger mission pool in SR4, that would be GOTF.
edit: Oh yeah, I miss the Boss acting like a Psychopath more often. I've seen one or two instances pop up, but it feels like they gave him/her the anti-hero treatment. Could just be the whole "saints are celebrities" thing at work.
Edit 2: Also, I haven't done Co-op yet, (my buddy hasn't gotten his copy delivered, fool went with 3 day shipping,) so I'm sure there are many more hijinks to be had therein.