Almost perfect, but sorely lacking in content to a painful degree. *UPDATED* Content problem mostly fixed by DLC.
The graphics are far above average, though the cell shaded look is a little flat. Yes, I know it isn't really cell shading. The explosions are gorgeous, and almost justify purchase of the game alone, and the solid frame rate only heightens the value of this already great game.
Sound is above average, but not perfect. The Radio guy is awful after the first 5 or 6 hours of play.
The gameplay is literally perfect, minus one little exception. The jumping feels even better than it does in Mario, and most of the controls are solid. The one problem is the awful lock on system, which is only bad because it won't change targets once an enemy is dead. It does not detract too heavily from the game itself, but is annoying.
The biggest problem with Crackdown is that the end comes too soon, as it is only about 20 hours long. Adding to that problem is the fact that there is no way to reset all the gangs after beating them. This means most people will begin to spam multiplayer for an excuse to replay the game until they get sick of it.
On the other hand, Downloadable content is on the way, so this should be rectified.
This is a great game, but it is just short of being amazing. As soon as the DLC comes out, the value should increase by a lot.
***UPDATED***
The addition of the new DLC makes this game a must play. Keys to the city is brilliant, and the ability to reset the game makes the replay value far higher. PLAY IT IF YOU HAVE XBOX LIVE!!!