There are a couple of great moments in this film: First of all, there is the weather. Similar to Key Largo the weather is menacing, shutting off communication though not completely. The telephone is still working, but of what use is that to a mute woman who tries to get help.
Although I liked the movie, I had the feeling that the "psychologisation" of the lead character - a trauma resulting in muteness - was too obvious. This also lead to some heavy handed script decisions, e.g. her trying to make a call and then realizing she was mute. (?)
But there are some other great scenes. The showdown on the staircase was quite amazing, and I really loved the the idea of the "threatening eyes" and the strong sense of POV throughout the film. A lot of times the camera watches out from the killer's head.