This movie is make or brake by Mcavoy's performance, and even though it didn't hinder the movie, it most definitely was not one for the ages. The film makes a premise, one which it develops along the way, but he knows what it is, even when things aren't quite how they should. The tone is definitely present and palpable although it was overstayed in the final scene when it required change but kept the same.
Not yet convinced that this isn't stigmatizing a serious mental illness, but it does yield a complex performance from McAvoy who has never been better. It's the best Shyamalan film since The Village and he doesn't have to rely on the often cheap device of a plot twist to provide an engaging story.
Really enjoyable film. Shyamalan managed to make a really suspenseful film with some really great direction. The writing though can be really spotty at times, with some weak dialogue and exposition. 2 of the 3 actresses are ok in their roles, but Anya Taylor-Joy and James McAvoy steal the show with absolutely fantastic performances. Also, great twist
Maybe bottoming out was the best thing that could happen to Shyamalan, for reasons not so much to do with his films as with his audience's perception of him. Walk into a film like The Village knowing it's from a "serious" director, and you might roll your eyes (as critics did) when it goes preposterous. But walk into Split only knowing it's a split-personality B-movie, and you'll be surprised how serious he can get.