I was planning to buy Prototype but the guys at my local games shop talked me into buying this instead (and those guys know their games.)
I'm not a big Batman fan but I love the gothic feel of the game. Essentially, Joker has taken over a lunatic asylum and is throwing a 'party' for Batman. The game is a lot of fun and it's easy to pick up and play; it's got a short learning curve.
My only gripe is that it is a bit easy. I'm 28% of the way through and I haven't faced any real challenges, even though the boss fights are ... tricky, but not tough. You get lots of hints, too. I guess I should have played it on difficult level.
Anyway, it's not enough to put me off the game and the storyline is pretty cool. All in all, I would suggest this game for people like me: people who don't play superhero games but would like to try something different.
Playing it on the 360, of course.