It's supposed to be about a 10-12 hour game from what I've read, which isn't bad.
I'm thinking of picking it up. I've been on a game buying binge recently though - in the last month and a half I've bought a 3DS, Pokemon White, Ridge Racer 3D, Dead Space 2, Crysis 2, WWE All Stars, Mortal Kombat, Bayonetta and Bulletstorm - so to say the least, I have a shit load of things to play and I'm not sure if I can justify the purchase of another game at this point in time.