I've been playing this all afternoon (release day) and it is amazingly fun and difficult. There are about 10 maps from what I have seen but there are randomized parts to each map that make it very different. On some maps you have to go for a safe, yet the safe changes location to one of a few locations, also certain entry ways or guards change so you cannot routinely go a certain way.
CAUTION: Do NOT play offline, if you like to play on yur own, expect to have the most difficult times imaginable. Not only is the online mode fun, it is the only way you will succeed at most heists, especially anything more than 1 star difficulty. The AI on this game is plain awful if you try to call them team mates, individually they are good as they will hold their own (although I've had a couple of occassions where they don't even move or come near me), but the AI in this game is the same type of friendly AI you would get in early current gen games like perfect dark zero or rainbow six vegas.
The major problem is that finding and buying this game is impossible. No, it isn't that popular, the publishers are just that poor. Amazon has no copies, since they were given very few in the first place. If you go online ou will see alot of people who cannot buy hte game direct from a shelf or anywhere online, also preorders are being pushed back until September (like mine was).
If you can find this game, get it (At least under £30, this is not a AAA title, it is essentially an XBLA title). If you are like others who are being told early September, xbox will put this up next friday on games on demand.
This game is the diamond in the rough. Plus there are alot more features to come in the future. The best game to waste time on until GTA.