I wouldn’t even say that his films are very violent at all. Sure there is violence in his movies, but I’ve seen much worse in other films. If any of Tarantino’s movies are VIOLENT, it would be Kill Bill. But in all of his others, the violence is always off camera.
In Jackie Brown, you never SEE anyone get shot! It’s always off camera or out of sight.
In Pulp Fiction, all of the more violent scenes are off camera as well.
In Reservior Dogs, the biggest violent scene is also off camera. Before Mr. Blonde cuts off Nash’s ear, the camera moves out of the shot.
Don’t get me wrong, I’m a big fan of movie violence and gore, but I think it would be unfair to say that Tarantino’s films are violent. Maybe here and there, but hardly enough to stirr up any attention. But what’s so great about this is that Tarrantino leaves the violence to your imagination. Leaving you only to wonder how bad the violence really is… 
