Way too ambiguous to be enjoyed...
Ugh. I don't mind ambiguous movies that make you as the viewer put the pieces together or even come up with your own story or ending. But there is a fine line between doing that in a way that is still satisfying and then just doing it to the point where it is becomes a muddled mess. This is a muddles mess.
It actually begins well enough with our main girl clearly in an unstable state and we get the impression she was like that well before entering the house. But by the middle of the film, the questions just keep coming and the answers at the end are confusing and not at all satisfying.
Examples... 1. What exactly did Dr. Abbott do to her? 2. Did she kill him or did she kill Henry Sullivan? She saw both names in his wallet. 3. Was the house even haunted at all or all in her mind? 4. Where did the black lady at the end get a key to go in with the cops?
See? These questions aren't just "oh, you fill in the blank and use your imagination type things." If I answered all those questions with just my thoughts, I would be making up an entire new movie in my head. I don't appreciate that.