There is a movement in Asian films for this sort of graphic visceral horror. It's making its way into American films.
The Japanese director Miike, who directed "Audition" (fatal attraction on steroids) has a cameo in Hostel. As sick and twisted as Miike is, he said Hostel was too much even for him. If you've ever seen a Miike film, that's saying a lot.
I hate horror movies but my wife loves them. I can't figure that one out yet.