I just watched this last night and while I thought the movie was actually pretty good, the Rifftrax was just so-so. While watching with the commentary, I just found myself drowning it out and paying attention to the movie. Besides the overuse of organ music and the lead actress' eyebrow, the movie had some great atmosphere and off-center themes. A bit genuinely creepy, it had a few Silent Hill-esque moments (the game, and I guess it'd be the other way around really). This is one of the few times I'm actually glad they have the original version of the movie on the DVD.
I'd give the Rifftrax a 5 but the movie itself an 8.