I'm giving this movie a very reserved thumb up, because of the music, the originality, and the astonishing Toni Collette. The story itself was riveting in the first 2/3rds, but for me, the ending blew nearly all the goodwill I had in my heart for this film.
I just loathe exposition! I think most of us were smart enough to figure out what was going on, without the drawn-out explanation at the very end. My understanding was that Aster added the exposition AFTER test audiences seemed to feel the need for it, but it cheapens the story, and lends more confusion overall. I can't understand test audiences being unable to grasp the plot so much that an explanation of that sort was necessary, in a film of this quality.
And the other truly off-putting thing for me about this movie is the inescapable conclusion that every single person in that family was doomed. There was no hope for any of them, and Annie's attempts to discover a way out of what her mother involved them all in, came to nothing. I'd have liked a bit of a chance for any of them, even if they squandered that chance by the film's end, but we never got a single moment of light. The utter bleakness and hopelessness seemed heavy-handed, and actually quite depressing, to me. Thus, it lost entertainment value, and became an exercise in perpetual grief and futility.
This movie was scary, creating dread from its very opening, and the family dynamic--the narcissistic mother, the unloved son, the remote father, and the odd, spectrum-ish daughter, was riveting. You couldn't look away, although you certainly wanted to. What Granny had bought with her soul for these people she allegedly loved was horrifying. The theme of unending abuse perpetuated generation after generation was given an updated and supernatural twist in Aster's mind. It was just a TOO relentlessly black and devastatingly hopeless vision for me, destroyed by silly exposition in the end.