I'm not sure where I stand on this. First of all, the NC-17 rating is a joke. This movie in no way at all deserves that rating considering this isn't remotely as gratuitously violent and a movie like Saw 3; I'm pretty sure this is just studio bias vs indie movies as detailed in This Film is not yet Rated.
That aside, the cast was great. Everyone was perfect in their role, with each character even more lame or pathetic than the next. Thomas Hayden Church was the real scene stealer, if you ask me.
But the story is just kinda there, and aside from the crazy finale, there isn't much remarkable about it, save for the great acting. And while the ending really does spiral into crazy town, I wasn't really all that shocked at all. Maybe I'm desensitized to stuff like this, but it didn't live up to the "sick and twisted" hype to me. There were some great, unexpected moments of comedy in it, like a certain moment involving a jacket sleeve.
In the end, my problem is that I just don't like movies about white trash people. I grew up with people like that, so, deep down, part of me hates seeing it in any form.