If your into movies that aren't "run of the mill" you'll like it. it is dark and demented, and you'll need to listen to some Jay Z or soemthing afterwards to bring you back to reality (lol). If your not into that go rent XXX or something.
As a sidenote while driving cross country a friend and I stopped at Xenia, OH, where gummo was set and filmed. It seemed like an ok place...till we stopped for gas...and I swear it was "Gummo" coming to life...