I came into this expecting a B horror/survival film which would entertain me for a couple hours. However, I got something a little unexpected and pleasantly surprising. The plot focuses more on character development and interweaves the story of the sadistic killer and his victims, so that none of it is as it seems.
The camera this was filmed with depicts everything in great detail. It is well put together with atmospheric music and pretty solid acting. While it is a well-made film, it is also an over-made film. The concept is not all that fresh, but there are some memorable scenes, namely (spoilers) when two frisky teenagers accidentally discover the "subjects".
You can see it done better in The Hole (2001).