This is an interesting film. The writing is solid enough and the acting is fine. The biggest drawback for me was the score. It is overly emotional and often the emotion being displayed on screen by the actors was being overshadowed by the overly emotive score. There were several instances where silence would have been perfect, rather than the single female voice wordlessly singing notes, which was overly used to the point of exhaustion.
The story is interesting. It takes a little while to get going and when it hit's it's stride it is a steady jog rather than a sprint. However, this pacing suits the film as the relationships between the characters needs to be established for the film's premise to truly work.
You can see that this film took inspirations from others. One which immediately sprang to mind was the Saw franchise, although with no traps and much less gore. More a case of being placed in a situation with limited information available to you and having to survive. So I guess in that way it is more like Cube. Overall it is a film which I would recommend, however NOT if you are a pregnant woman!