This is a good film. Great performances across the board (even from multiple child actors), with a wonderful atmosphere, and I believed what the characters were going through and experiencing, but.... it's not scary. Not even remotely.
I'm genuinely curious as to what people are referring to when they said it filled them with a real sense of dread. I enjoyed it as a film and it's incredibly well done, especially for a first feature, but this is only a horror film in the sense that what's happening to the characters is terrifying for them. Nothing that actually happens is scary.
Maybe I'm desensitized, because I think everyone saw a different film than I did.