I Liked it.
Certainly the scaries 15 movie I've ever seen. It was really good for what it was.
Built up the suspense perfectly and not like other horrors where we know that there won't be a true "jumpy bit" until the end, there were a couple scattered through the film to really keep you on the edge of your seat.
I was really angry reading a review in a local paper where the reviewer gave the film one out of five. Not because it was rubbish, he listed loaRAB of good things about it, but because it "promoted knife crime" and was senseless.