I really wanted to love this film, because I felt it was an honest attempt at delivering a stylish, disturbing and original horror film.
In places, it does deliver those things.
What didn't work for me was the characters. The fact that they were mostly cocky and dumb teenagers, gave this film a strange vibe; Like it was trying to be a Hereditary / Ouija crossover, but with the irritating shallowness of the characters watering down the experience. Mia is the only character with any real depth in the film, and the others seemed to change their personalities and opinions towards each other on a whim, just to suit the plot. While many of them are reasonably well acted (Mia being the standout performance), there are a few generic and bland performances in there too. In short, an interesting film that executes some of its ideas well, has some good twists, but is brought down to earth by poorly written characters and lack of real emotional impact.