This is a pretty good book, tense and gripping. It is an SFF thriller/horror and definitely creepy and atmospheric. It is middle grade and doesn't contain anything I would personally consider unsuitable for most pre-teens. 

Where it perhaps lacks a bit is in its characters - I rarely felt much connection even with the central characters and it didn't pack as much of an emotional punch as I would have liked for a book where so many characters are forcibly separated from their families. If you're mostly looking for a spooky, atmospheric read though this is a good choice.