I can check "watch human centipede" off my list now.
I expect that for some people, knowing the premise of the movie will lead you to imagine something much worse than was actually shown. I was surprisingly unfazed by most of it.
Instead, the main feeling that I was left with was annoyance. Without spoiling anything, I was annoyed at all of the many times that characters were given the chance to do something more intelligent.
Of course, we wouldn't have this movie if people had been more intelligent.