We have seen the story before... trapped in a mine, a group of people struggle to survive. Yes, we have seen it and similar stories more than a few times before, but seldom so well. Solid acting quite effectively conveying fear, despair, and madness; a crescendo of well paced action, a VERY claustrophobic setting, a compelling twist of the unexplained, all blended together to make a real movie out of something that could have just ended up a clone of many others. I say this even admitting that I am not usually a big fan of movies with premises like this. I really liked descent (the comparison is, in some ways, inevitable), but didn't love it as much as some, and yet I put both these movies on par and rate them highly (for me a 7 is high... the mark of a movie well worth watching). If you are one of those people who loves this type of movie, I suspect you will rate it even more highly than I did.
If it could be faulted it is that the mystery madness (without giving too much away) is never thoroughly explained, and this contributes to a rather notable question mark at the end. It did not bother me... I find the mystery compels us to feel confusion in a way similar to the characters themselves, but for some viewers it will stick in their craw and they will cry foul because the director didn't spell it out for them. But this is a character and survival piece more than anything, so it can be forgiven if it defies leading us by the nose through a neatly sewn up narrative.
With that said, make what you will of it. Sit back with the big screen and good surround sound if you have it, and a significant other maybe, and enjoy.
