Very high on the "yell frustratedly at the protagonists" meter. The first act has a ton of promise though, reeeaaaally creepy. That big fast scary truck!! Extremely visceral stuff. Justin Long and Gina Philips turned in some good performances.
It loses a lot of juice when it becomes a creature feature and that's coming from someone who normally really loves a nasty goopy prosthetic guy. I was much more freaked out when I thought it was just an evil backwoods weirdo.