What I liked: It takes the horror seriously (none of the Scream meta jokiness); the monster is cool, it opens with a child's death.
What I didn't like: apparently no one has a cell phone light, no one in the house can hear anything that's going on, the one character you want to see die doesn't, and people are so dumb it pulls you out of the film.
It's frustrating when a film has some solid craftsmanship and promising elements…