This movie can be summed up in one word. Anxiety. I don't think I have seen a non-horror flick that made me so physically uncomfortable to watch the twists and turns in my life. Loved every minute of it.
Edit: while reading the other reviews I see some valid criticism. Most of it seems to revolve around the mostly unlikeable (intentionaly I'd imagine) characters ,and the fact the movie produces as I'd say earlier anxiety, a feeling most people seek to avoid. That is fair. I can understand that.however that aside I still stick by my original score. It brought about an uncomfortable energy to the very end and that isn't always a negetive.