It is a family-friendly horror film. Know that going in and understand some of the scenes are too scary for very young kids. I would say 8 years and up.
It is an original story and a very good movie. My daughter, 8yr old, and friends loved the movie, but would not have been comfortable watching without me.
Afterwards, they could not stop talking about the film and immediately went home to "sketch" their monsters.
Go and enjoy an original story. It is much better than the recycled junk, ie Superman/Fantastic 4.