The slam dunk thing is pretty cool, though I totally suck at it, so I haven't done too much with it. The game is good, but still frustrating. Some of the off-ball stuff simply doesn't work: sometimes a guy won't set a pick no matter how often you press the set pick button. The CPU pro-hops too much and blocks too many J's, but sliders can fix that. You still can't rely on your teammates to play good D (yes it's still fun to watch your two idiot teammates in the backcourt move *away* from a breaking opponent because they aren't supposed to be matched up with him <sigh>). Freestyle Air is cool to watch but not too useful unless you have a tight camera angle (I prefer to see the court) or maybe a really good TV so you can see close enough to know what to do. Overall I'd say it's way better than 2004 (which was good) but still has some maddening problems. If I knew for sure that they'd patch the PC version to improve stuff, I'd sell my Xbox version to get the PC version. But, they won't so XBox it shall remain (I'm ready to give up on online play entirely at this point).
I don't think I'll be getting ESPN NBA 2k5 because I never liked the 2k series. It doesn't "feel" right to me. Maybe if they cloned Freestyle better maybe I could get into it.