Well, it's not as bad as you say...
I watched the movie, the plot is original, and the character buildup is fine. I started to sympathize with the girls, and liked Sophia.
Amber scene eating her friend is awsome, a lesbian sexual symbol. Sure she can eat well.
I guess you need to spend a night in that resort to become evil. But the rest of the girls are already bitchs before getting into the resort.