I watched this film with my family last night. My son is 12 and just about old enough for it as it is classified as a 12A, although he enjoyed Cloverfield which was classified a 15. The film is a ghost story and one that contains very little dialogue really. There are jump scares and unsettling images of children committing suicide in various horrible ways.
My son watched it however, it was very creepy and he didn't want to sleep in his room when he went to bed, so he came to bed with us for a while. he did eventually go to his own bed, I'm not sure what made him go.
I enjoyed the film more last night than I did the first time I saw it. It is a pretty good version of the story, I'm sure I've seen it in various iterations in the past. The shocks are quite effective. It would leave me feeling scared as a child as well. Overall, not a bad film. It's not gory, so would be fine for people who like ghost stories without lots of special effects and blood and guts.