OK here's my little review after playing the game for a couple days.
Gameplay - Very good. Easy to pick up, fluid. Just really fun to play. They changed up the gamebreakers a little bit and I really like what they did with that. There is no time limit on it, and if you steal the ball from your opponent you can sue their gamebreaker. Double dunks add a whole new bit of strategy. (they are worth two points, but if you mess up you get blocked by the rim)
Graphics - Also very good. The players models are great, very recognizable. The animations are also very cool, and the new dunks (particularly the double dunks) look great.
Campaign mode - Not as good as it has been in the past, but not bad. You basically just play a series of games/challenges, hopping from one court to the next. Unfortunately it appears that so far you cannot go back to previous courts which is kind of annoying. Also you can only have 3 players on your team at a time, including your created player, so you dont have a lot of different "looks". Leveling up is also a little different. Your abilities go up as you use them in real games, you dont just earn points and spend them as you like. General exp points make you gain "levels" and generally increase your stats. At level 5 (very early in the game), you choose a "freak" skill which instantly maxes one skill out to 100. I'm not sure how I feel about this, kind of ambivalent. Just a little extra feature.
Customization - This is the major weakness of the game. Create a baller pales in comparison to V3. You dont have much control over your player's appearance. You basically choose a "default" face, including hair style and skin color, and then choose to NBA players to "mix in" and change the face shape. But you cant mix and match facial features, hair, skin, eye color, etc. Also, the "gear" is almost non-existent. The only gear available are shoes and "outfits." You only have 2 or 3 choices at the beginning and you slowly unlock more by winning challenges. But in this game better gear gives you more exp points as you play games. So you dont really get to choose what you wear. Its lame.
Overall its really fun to play, but like most sports titles when they debut on the 360, the lack of options and customization sucks. Still worth buying if your a fan of the series, especially if you play online. But just prepare to be a little disappointed if you liked the create a baller (and create a park which is gone) from V3 like I did.[/b]