While I didn't find anything about the movie to be particularly poor, I can't really point to an area where it really excelled either. In many ways this is the absolute definition of just a stock horror film. It's almost like having been on a ride that you have been on multiple times in a row. While it's still enjoyable you've kind of already been there and done that. This quality of movie is fine for once and a while, but you wouldn't want to follow it up with a similar level film. The acting is average, but there's nothing that really draws you in to the story that makes you care deeply about any of the characters. To me that is what defines a horror flick.
The ending suggests the possibility of a sequel, but I'm not sure it's earned that.
