Loved this movie, but not for the clever reasons you guys did...
I'm a big fan of horror, especially realistic evil. Stuff like Hostel, Irreversible, and Eden Lake. I loved this movie because it was so dark on a psychological level. The victims were degraded mentally and emotionally abused...all under their own ridiculous social customs involving mannerisms.
And I'm not a masochist like so many people seem to assume you must be to like this movie. And you don't have to interpret this movie as making fun of the horror genre either.