I thought the film was allright. It was a nice "try and figure it out as you go" film and you don't necessarily know who the antagonist is right off the hop. Even as you start to get an idea of what the characters are facing, it is a fairly non-traditional approach to the genre IMO. The only part of the movie I really didn't enjoy was the very end. It felt a little too contrived and convenient for me. As far as the performances, I thought Julian Moore's was solid and engaging, although I can't really say the same for the rest of the cast, who came across as a little flat. One one hand this does have the effect of making the whole piece a little more sureal (sort of like Moore's character's bad dream), I found it distanced me a bit from the film and kept me from truly becoming engaged in the story. Gary Sinese was adequate but didn't have a large role. I saw one critic on RT describe it as an average episode of the X-Files, which in retrospect is an accurate comparison as far as I'm concerned (although that didn't occur to me while I was watching the flick).
On a scale of one to ten, I'd say I'd give it a 6. Some good startling moments, an interesting premise and fairly creepy atmosphere, anchored by Julian Moore's capable performance. A weak supporting cast and contrived ending brought it down for me however.