Good movie, good twist.
I saw this movie with some friends and I loved it. Nothing really pops out at you, and it's not very scary, just suspenseful. The thriller stuff (just fight scenes, really) come towards the end only, so the scare factor isn't that high. Sexual references aren't that prominent, so if you're kid is mature, they'll be fine. The scariest thing in this movie (to me) was the gore, as you see a man's hand sliced so that the fingers are separated, and a girl gets stabbed in the leg (and pulls it out). Try not to look if you're squeamish. There is drug use, but it's not glorified.