Without giving too many spoilers, I just have to say that, despite my open-mindedness, there are too many issues with this film to have found it even the least bit enjoyable.
A few of the things that made me dislike it from the start had to do with over-acting, and ignorance of the relation between the characters and their environment. For instance:
-The characters are all in their underwear, complaining about how cold they are. Why, then, are there no goosebumps, or hard nipples? I'm not disappointed from a sexually based standpoint, I'm disappointed because I can't believe anything when the character is obviously warm and perspiring lightly but complaining of the cold.
-When the lead actress wakes up confused, her movements seem almost robotic, and jerky. Fine, but then she hears a noise, and her facial expression goes from confusion to, I don't know what. Not fear, as far as I could tell...just a blank stare. Bad emoting, in my opinion.
-The padded cells are beautifully clean, and bleach-white inside. Yet, the rest of the facility is run-down, dirty, and neglected...such a stark difference between the two is really disconcerting, and seems wholly unrealistic.
-The story never explains how the lead actress's door opened on its own, or even deigned to attempt any explaination. Not too bad, but it just adds to the confusion.
-Why on Earth does this place have an Olympic size swimming pool? There is nothing I could even imagine it would be useful for, knowing the nature of the facility.
To go on would give away too much of the story, so I'll just say that I could go on, scene-for-scene, in the same fashion.
Overall, the concept was interesting, but the execution was terrible.