It's a film that's really split people down the middle since it premiered at Frightfest last summer, with people either loving it or hating it and not a lot of middle ground...
... I loved it.
People will complain about the changes in tone, but it's a film that gets better with repeat viewings, knowing the twists and turns the story takes. Sentimental and emotional bits on among the gruesome scary ones, which is a nice change (particularly like the Timothy Spall cameo).
Check out Philip Ridley's first two films, The Reflecting SKin and The Passion Of Darkly Noon, if you can as well.