Wow, ridiculous
Sorry, but aside from the concept, the movie itself was ridiculous and horrible. Some points to note:
1) Horrible acting start to finish...especially the part where he got his leg crushed under the car. He's screaming bloody murder and then suddenly he's out like a light.
2) Are we really supposed to believe that once the original bullies were gone, that all the lower kids suddenly became bullies? Sorry, that just doesn't happen. Maybe one or two, but all of them? No...especially the handicapped kid.
3) The kid had his leg crushed underneath a car. He can't walk on that leg at all anymore, but he can still manage to push a van down the road (when killing Paul)? Really?
4) When the bomb exploded and killed him at the very end, the explosion was very small. That sort of explosion isn't going to level an entire school. It would barely do any damage outside of the room it was confined to, which appeared to be in the basement.
5) Is it normal for a girl to walk in on a gang of guys raping two girls and to just laugh about it and stand around waiting for her friends and watch? And is it normal to get mad at the guy who comes in and rescues them, saying he's just as bad as them. Hmmm...raping two girls or saving two girls from getting raped? I don't see how they're the same.
6) This veers away from nearly every horror/slasher film I've ever seen in that the main bad guy (or main character) was killed off first. Bruce was the jerk ringleader of the gang of bullies...logic would tell you that he'd be the last of them to be killed off. Usually you kill off the henchmen first, and then the main guy goes. This isn't really a complaint, just an oddity in the film.
7) The guy who jumped in the pool had his head crushed and his face was driven into the bottom of the pool. Nobody touched him, so how did they all know that it was Craig? Surely they couldn't identify him from his face as it was crushed and face down in a pool of blood.
8) I found it funny how Mark was chasing the runaway van down the road as Paul plummeted to his death. Then he overlooked the cliff as the van exploded and pretty much had no reaction. He didn't run to the scene, he didn't show any emotion, he kind of just walked away and was like "Oh, well crud, Paul died."
I'm sure there were more oddities and unusual occurrences/plot holes that I noticed, but these were some main ones.