It features James McAvoy playing a man with multiple personalities. Never mind just 3. He has 23! Plus a 24th called "The Beast", which adds a horror aspect to the film.
Many reviewers comment on the director and writer, M. Night Shyamalan, because he made another popular movie "The Sixth Sense" that I haven't watched. My impressions are based on what I see up on the screen in this film.
McAvoy is first-rate. He's one of a number of younger actors who are competent, have some charisma and can handle a variety of roles. I do not mind watching him in the lead at all. The older gal who plays his shrink, Betty Buckley, holds up her end well. The younger female roles are not as well defined in the script, except for one of them, and she's introverted and doesn't have much to say; but she's convincing.
I would say that the whole thing was not tight enough, or written and directed too loosely. It just didn't grab me emotionally or intellectually as such a promising premise should have. For example, once two girls are locked in separate rooms, we hear little of them. We do not really see what happens to them. Certain parts of the story are elided. This director is certainly no Hitchcock. The writing seems as if it was reaching for a theme, but the one that it explains wasn't very convincing.
Anyway, it's quite interesting for a script to assert that the fractured multiple personality individual is somehow a superior being. This in earlier days would have been called delusions of grandeur. In other words, insofar as this story is reflecting our society, it's saying that the demented are superior. This shows an inversion of normality and a disposing of values. It's a message that Western civilization is being eroded by some very strange ideas and we're seeing them placed up there on the big screen as one mode of transmission. Maybe some of that director's other work reveals his state of mind.
"The Sixth Sense", from what I read, also has a patient-doctor frame, and the movie suggests depths to the mind that are unexplored, just as this movie does. My guess is that the Indian background of the director helps account for the strain of Eastern mysticism that's behind this kind of theme and/or the supernatural aspect. Not exactly nirvana but some sort of relative thereof. I do yoga and have for a long time, but I'm unimpressed by Indian religious directions and their outcroppings as in "Split".