Interesting
The pacing of this movie is very slow, and it's not a jump-scare film, so if you like conventional horror it's very possibly not for you. However, the unique, methodical approach both of the visuals and the story progress make for an extremely uncomfortable, eerie atmosphere that I think is really effective. It's clear this is an experiment, and I think a largely successful one, though I admit it feels much longer than it is.
I think the idea was to approximate the feeling of something unsettling and inexplicable (like a haunting), and in that I think it works very well. This from someone who absolutely does not believe in ghosts. The subject of the film is broader than that though - it deals with the feelings associated with such topics whether imagined or otherwise.
On the whole, I give it 6/10, and would call it far better than most of the crap being pumped out these days.