Completely enjoyed this.
I do disagree with the homophobic tones mentioned by the other posters but understand where they might see that. I won’t spoil anything but I highly recommend it. High suspense and gore.

A shout-out to Alexandre Aja’s High Tension, an absolutely nerve-wracking, taut thriller machine, told with minimal dialogue and an impressive narrative economy. It also boasts of one of the more malevolent villains in recent film history and surely the most gloriously horrific use of a rotary chainsaw in a film. Unfortunately it’s marred by a frankly insulting twist at the conclusion and appalling sexual politics. (Even more so, Aja’s gift for gore is squandered in his second film, an unnecessary remake of Wes Craven’s The Hills Have Eyes.)

suppressed homosexual desire in a lesbian + psychosis = alternate identity as an incredibly ugly male serial killer

and it all adds up to a boring and homophobic film

In terms of suspense level (blood aside), and twistasticness, I fit this movie into the same category as The Machinist.

Good direction. Bad plotting.