I approached Split with some reservations; past experiences with M. Knight had left me uncertain if it would be enjoyable. However, the promotional material was appealing, and I’ve always considered James McAvoy to be a remarkably talented performer who doesn't get enough recognition. Split ended up being quite good. I really enjoyed this film. Ann Taylor-Joy gave an acceptable performance, and the doctor’s character was well done, but McAvoy truly excelled. His ability to embody so many distinct personalities without relying on things like wigs or makeup is a testament to his skill. It was remarkable how one persona could evoke feelings of discomfort and confusion, while another elicited smiles and made you feel as though you were observing an unusual child. That was impressive work, McAvoy. The ending offered something extra that deepened my appreciation for the movie, although I’m not certain “twist” is quite the right term; perhaps "reveal" would be more accurate to describe what the audience discovers. Whatever it's called, this reveal left me eager to see what comes next. My only criticism concerns the unfinished issues between Ann Taylor-Joy’s character and others at the film’s conclusion. Apart from that minor point, I thought it was excellent. It’s certainly worth seeing.

Source on TMDB