Its not a horror movie and thats that. Yes, it is way over the top, but in the same time it has some meaning behind it. Think about the setting, the cultural background of the characters etc. Its about the perverted human nature, and there are plenty of symbols to be found IMO. yes it was done before, in different ways, but this one actually atracts attention, and in 2010, its not an easy thing to accomplish.
The thing that Im more disgusted is that people call Avatar a masterpiece, and then bash this movie. Dont watch it as a horro movie, watch it as a satire, and you to will find something to love about it. Cant wait for the second sequence 