Eh. This is a popcorn movie, nothing more. I watched this with a bunch of friends (and though that might NOT be the best way to view a horror movie...) and most of the dialogue and action was laughable.
It left me yearning for a real film. :)
The main problem is the lack of tension in the film. It keeps flashing back to 'explanation' scenes, which dissipates any discernible tension.
And the character relationship 'twists'? Yeah, they suck. I won't say what they are, but they just don't add anything to the film/storyline.
(By relationship, I mean the two main characters.)
Eek. My recommendation is this: watch this movie if you can't think of anything better. Mediocre at best...Maybe not even that.