Yeah, the movie was filmed for $2 million and has already made it back with only a limited release (think they just expanded to 1,200 theaters this week). While making money is for sure important, the movie itself is pretty artsy so mass-appeal will lag critics IMO and gauging the investment they probably figured this....leading into, the review!
So, I finally had a chance to see this last night and was OK with it but a bit letdown. The concept behind it was pretty original, albeit with throwbacks to others (had some strong Halloween vibes for me). The score and story-telling I feel were strong and without these elements this would have ended up your typical 3/10 teenie date movie. I gather this is the director's, David Robert Mitchell, first go at horror but he did a great job presenting the 'monster' so it wasn't in-your-face obvious (most American horror these days) or WTF-is-going-on confusing (looking at you Korea and Japan) so you can actually get just enough to track the story with your mind filling in the blanks to personalize the suspense. As mentioned, also excellent use of sound to raise tension (think the siren in Silent Hill). There is a lot of symbolism and metaphors throughout this movie and I'm sure film students and artsy types will love it but it was all a bit too try-hard for me, taking away from what could have been more terrifying.
For an artsy-movie, I'd give it an 8/10. For horror-fans, a 6.5. It was worth seeing in the theater for me, just because it was shot well and the audio was such a big component of the film. That said, I think you'd still get the point watching it at home.