BUYER BEWARE!!!
I have a 6 month old, fairly powerful PC.  I've yet to encounter a game I can't run at max settings.  I downloaded this game from Steam at the day of launch, installed it, and there is a game ending bug.  I cannot start the game.
I go online looking for fixes and finds hundreds of users on the 2k forums alone, all with the same problem.  I am using windows vista, not some arcane obscure operating system.
So far to this day, not only is there not a fix, but there isn't even a post on the 2K forums stating there WILL be a fix.  This was a download; I can't return the game.  If I could I would just buy it for my xbox.  The fact that I cannot even start the game is an indication to me this is not a performance bug, but rather a problem with something basic on my machine.  The problem there is, I haven't taken the time to fiddle with this machine.  It's pretty much in 'fresh out of the box' status, so for a game not to work at all is frustrating.
Anyways, there you go.  My roommate bought it for the PS3 so I've been playing it; not as good as the first one, but still quite good.  But frankly if 2k doesn't put out a fix for this, I won't be buying their games again, and there is already talk of a class action law suit unless they provide refunds.