Ok guys, I am a ps3 user, but my flatmate has quite nicely donated his xbox 360 to me for a day so that I could get a hold of the demo and post my impressions. I am a 2k basketball fan, but I have attempted not to be overly biased.
Ok so let's start with the not so good things:
- 2k seemingly still has this annoying animation that when you absorb contact in the paint, you sometimes end up shooting at the back of the backboard, obviously resulting in an out of bounds call. This would very VERY rarely ever happen in real life, definately not in the NBA.

- This has only happened on occasion, but sometimes on a break (and even in halfcourt ball), I would attempt a normal pass to bynum or gasol, and it would somehow become a (failed) attempt at an alley oop play. Not good.
- This is one thing that no game as (successfully) implemented... On a fast break you still cannot whack a player to stop the break and/or dunk. Many times with kobe and fish i just get caught running behind carter and becoming a background image for his poster

- The most neglected thing about 2k is the kicks in the game. To put it in simple terms, they are horrible! I know a lot of people do not really care about them, but they do suck. All of the magics shoes look exactly the same, except V.C has a nike tick and Dwight has his 3 stripes. At least kobe and gasol's nikes are respectable. (I just hope you can make the Kobe IV minneappolis colourway, cause I wear them haha).
- Still no MVP chant for Kobe? cmon.. the laker fans need it lol

Ok now to the things I enjoyed about the game:
- The new turbo system is fantastic, I love it. That's all that needs to be said. And the fact that it uses turbo to play lock down D is great as well, my mates might have to learn how to play D now

- The crowd shouting chants when the away side shoots charity shots is good, I believe that they are saying "your gonna miss" or something along those lines.
- Arena sounds are excellent, along with sounds on the court (shoes, net, players, etc)
- Player models (as always is the case) are brilliant, they don't look like shiny plastic men (like in another certain game)

- A little thing that added realism to gameplay was the seemingly new block animations... different from 2k9's lackluster effort, the 2k10 animations look better
-

Slam dunks have been towned down. Enough said. Any 2k user will know what I am talkin bout.

- Fast break animations are good, they are fluent, and provide the user with a variety of options, and every player defends a break differently as well.
- The way that the crowd responds to whatever the situation is in the game is fantastic

- The presentation that we have seen looks top notch as well, from halloween games to christmas games, to commentary to the instant replays, 2k10's presentation will not be matched this year

Overral I would probably give this demo around a 7.5, as it is missing key components of the experience, such as commentary, ability to make subs and run plays, and more game time (to see how players play down the stretch).
From what I have seen and gathered on 2k10, along with the gameplay I experienced however, I am going to give 2k10 an early rating of 9.
I will be posting impressions on the "My Player" mode once I have the game on Friday. Thanks for reading.

Impossible is Nothing.