I really liked it up until about 2/3 in when it derivatives from the books. That was really disappointing because it felt to me they closed off the story with no intention of ever producing a sequel, or sequels. Without giving too much away the 1st book ended 'up in the air' and the 2nd and 3rd continued the story, building on Jacob's (not Jake!) peculiarity and intensifying the sense of mystery, foreboding and threat from the peculiars who'd gone over to the dark side so to speak. In short I felt the film ended up 'dumbing down' the whole concept ..... presumably so it could be marketed to a wider audience including younger children, but IMO the books were really aimed at an older teen and/or adult audience despite their 'fairytale' style.
I did think Eva Green was very good, and the characters of Jake and Emma were realised well ... and the peculiarities of each child were cleverly conveyed. But the ending kind of degenerated into slapstick and overall, the film simply didn't have a depth to it like the books did. I got a real sense of peculiar history from the books the film just didn't have.
And yes, I wouldn't recommend it for kids under 12!