Throwing in my two cents too...
First off: Not scary in the least. I think I jumped once in on a fake "gotcha" moment where someone came out of nowhere.
2) I thought the last 15 minutes was a clever and creative idea but I left the theater imagining all of the other, much more cooler and suspenseful ways they could of executed it.
3) The most implausible plot set-up since Stonehedge was moved to California to make snake-producing Halloween III masks.
4) Loved the surprise cameo though.
5) Hated all of the supposedly funny stoner jokes that feel flat everytime they hit.
6) The very last scene before the credits. Really?