I finally saw this last night. I thought it was good, but not as good as it's been hyped to be. The cinematography and especially the sound were amazing. I didn't like that it was sort of a one note movie, my emotions remained in the same state through the whole film. Dark. But worth seeing on the big screen.
Spoiler Below Yeah, I think it was all in her head.
EDIT: Some people haven't seen the movie people. - SK