I was interested in renting the DVD. I wouldn't see it in theaters in case the violence got too rough for me and I wanted to turn it off--though I did watch the first six minutes online, and liked the crazy and intense direction/editing style despite being bothered by all the blood. The feel very much reminded me of one of my favorite games, "Max Payne." However, I read a review of it that said it had a lot of violence against kids in it, and that always bothers me quite a bit (though I did adore the disturbing but very-moving "Unleashed," which had just a bit of it in a flashback sequence), so I probably won't wind up seeing it at all.
I think, however, that this movie is Paul Walker's "Butterfly Effect." Like The Kutcher(TM) was with that film, Walker is viewed mainly as wooden "actor" who's in a lot of crappy movies, but then he comes out with a movie so crazy and messed up that you have to take him seriously for once.