I just played the PS3 demo. It's not my kind of game so I won't be buying it but, man, it's by far the bloodiest demo I've played.
I rented it after playing the demo, and it was fun and everything, but it got extremely repetitive after a while. You fight basically the same five or six enemies throughout the entire game. About halfway through, I just stopped caring. I don't know how far along in the game I got, but it was probably about 60%, and then I stopped playing.
It was ok to me. About what I expected. The graphics were jagged, but some things looked good. The fighting seemed simulated. Just a pure button mashing game. Could be fun as a time killer.
It was really fun when I first started playing it. But once the novelty of 'hey look what I just did to that guy' wore off, it got boring.