This movie is not for the faint of heart.
Others have called it bleak, brutal, and depressing. And it is. I ignored all that and went in thinking it'd be another British neo-horror flick like The Descent, but boy was I wrong. Now, don't misunderstand me: it is a horror movie but in the most literal meaning of the term. The events in this film are horrific, and it leaves you feeling horrible at the end. To tell you why would require spoilers-and I won't do that-but you might want to spoil it for yourself to save some heartache. Let me just say it doesn't have a happy ending. You can thank me for that warning later.
I get why the rating is relatively low, and I don't begrudge anyone their low scores. It is not a movie for everyone and isn't trying to be. I can't say I liked it or enjoyed watching it, but films so rarely leave me palpably affected. I had no choice but to give it a higher score. I'll probably never watch it again. If you watch it, I recommend having a collection of funny cat videos on standby. But the movie is excellent. Bleak, brutal, and depressing for sure, but excellent.