
Best thing: Wonderful build up and atmosphere and a real sense that the main character has dark hidden depths.
Worst thing: The protagonist's "friends" have no depth at all, seemingly don't really matter and we ultimately cannot care less about them when the film turns into an uninspiring slasher movie towards the end.

Half way through this film I was loving it. A woman prepared to do anything for a chance to be a star, with heavily implied Lovecraftian themes and some cool atmospheric and suggestive effects indicating our protagonists transformation.

The problem is that the climactic third act requires us to care about our protagonist's horrible 'friends' and I just couldn't. Perhaps if we were able to be happy about those deaths it could have been fun. But we are clearly supposed to be shocked. Really I was just confused. Shouldn't she have transformed into a monster BEFORE she kills people? I wonder whether they couldn't get funding for an exciting monster effects filled third act and this third rate slasher rubbish was the cheap alternative.

Endings matter and the final third of this film is seriously unfortunate. However, there was a lot of potential here and the end product remains pretty watchable.
C-
P.S. Discovered this one through @catcavecinema and to be absolutely fair to them, they warned me. Still, their review intrigued me so much that I felt I had to see for myself....
The Other (1972)

Best thing: The central actor is playing two separate twin brothers. While I don't think his acting is especially mind blowing, it's pretty impressive that I am never confused as to which brother he is playing. There is a reasonably subtle distinction between his performance for each brother. - Except... now I come to look it up, they are actually played by two actors. I’m not sure why they always show them in separate shots, but I guess it might be a strength of the film that it kept me guessing on this issue?
Worst thing: The supernatural can very easily annoy me in films. Sometimes some crazy supernatural antics are all part of the fun, whether it's a cursed videotape or a magical cloak, but when we get to ghosts or psychics, sometimes films seem to take plausibility for granted. In "The Other" the boy apparently has some odd sort of power which allows him to inabit another person (or at least imagine he is doing so). With such a vaguely established power and confusing consequences, I found it hard to take seriously.

The Other is the story of two identical twins. One has a good relationship with his Russian grandmother while the other wants to do bad things and may have killed someone.

I originally heard about this film when looking into horror films about the fear of children. Films like The Omen, The Exorcist, We Need To Talk About Kevin and Who Can Kill A Child. So here we have a story about an evil brother. The performances aren't bad, but I don't know that the direction is really doing much to build up an atmosphere. This felt to me like a naff tv movie tone.

I will admit that the big revelation did feel genuinely creepy, but I also felt that the movie had no idea what to do next. Considering how slow paced and flat this film is, it's perhaps a little remarkable this was even as watchable as it was. Still, I can't say I was a fan.
D-