I don't get all the venom spitting...

Rating: 8/10 (17 May 2017)

...which goes on about this movie. I liked it greatly. The suspense starts within a few minutes from the beginning, and never releases its grip until the final demise. The mean actor is absolutely great in his performance, playing 8 different personalities was not an easy task, and he did accomplish it with awesome skill. The setting of the story is totally creepy and perfectly fit for the character and the tale that is told, the soundtrack is carefully chosen to masterfully accompany the gloomy, sick atmosphere, and what about the story itself? It has a few minor flaws, but it works more than fine, and reading other reviews I notice that many didn't get important details.
Casey's flashbacks, which many have deemed useless to the story, are instead a key element in the lunatic's final attitude towards her, and his seemingly unrealistic transformation (the most impressive one, I'm not going to say more in order not to spoil anything) is justified many times in the course of the movie by the description of how different personalities in one single person can have each their own physical peculiarities (such as illnesses etc.) which the others have not. Sure, the transformation itself a bit exaggerated, but the sense remains the same. And anyway, hey, it's a movie! You're expected to apply a certain amount of suspension of disbelief. Otherwise, just watch documentaries.
As in just any horror/thriller movie, there's a few "I-have-to-act- stupid-in-order-to-keep-the-movie-going" moments, but those are to be expected, and don't take anything away from the enjoyment anyway.
All in all, this is a very good movie in my opinion. If you like thick suspense and psychological twists, just watch it and you will enjoy it.