Tl;dr: Ignore the spammed rating, we all know Uwe Boll is a reliably terrible director, but he pulled off this one good film in his life. Good acting, good premise, believable characters who's motives are understandable given the context. It's pretty bleak, but if that's what you're into, it's a great way to spend an hour and half.
If I have any complaints about the movie, it's in the editing and (lack of) script. First of all, the movie is frequently intercut with interviews/interrogations of the surviving inmates. However, there is nobody in the movie actually questioning them. Often they'll answer a question and the audience doesn't have any context. It's my understanding that much of this film was improvised, which really helped the conversational madness of the scenes in the cell. But occasionally, you could tell an actor was stuck trying to think of something to say, which leaves a few awkward pauses and strange phrasing.
Other than that, for a movie that mostly takes place in a single room, it's quite entertaining. The pacing is great; you'll never be bored. There's some great acting, especially from Sam Levinson who you truly believe is traumatized. In his interview segments, he gives a very emotional performance. He acted with his hands a bit too much, but other than that, I'm shocked he hasn't done more serious mainstream dramatic roles.
The worst performance comes from John Connor from Terminator 2 (once I realized who he was, that's all I could think of him as). He's not terrible, but he plays the most remorseless character, so it seems like he's trying too hard to be a generic sociopath. The German dude was pretty good too.
Obviously the movie is dark and depressing, but if that's the kind of thing you're into, I highly recommend it.
