Bulletstorm has potential to be a really good game I think:
Looks great and has a nice mix of moves and weapons to provide variety and allow for imagination in combos. The easy moves (VooDoo Doll, Bullet Kick) are fun, but could get old quick - it's the combos where the real fun could be had. Leash a dude, stick him with the flail gun, then kick him back at a group of baddies and watch him explode... fun stuff.
Characters in the game don't seem to take themselves too seriously, which makes perfect sense for a game with over-the-top killing sprees/methods. This game rewards you for pulling off cool shit, and acknowledges it when you do with both on-screen and vocal feedback...People Can Fly seem to have done a good job with this. I was somewhat interested in this game before and buying it for the Gears 3 beta, but the demo sold me on the game itself. Really looking forward to the full release now!