Simplistic Reviews’s review published on Letterboxd :
Word around the campfire is that M. Night Shyamalan is BACK! It's like he's John Wick all of a sudden.
If it wasn't for James McAvoy this might also just be another middle-of-the-road attempt, but it's almost impossible to look away from what McAvoy does. I don't think there is anyone else in Hollywood that does so much with so little. Just look to the last 20-minutes of "Split" and you'll get your money's worth.
This time, Shyamalan's "twist" works quite well and makes you think back all the way to his earliest films and gives you pause. Of course, I won't give up the "twist" because this time around, it's that good.
The verdict is still out for me on Anya Taylor-Joy. She plays the "babe in the woods" role very well, and I did enjoy her character arc from beginning to end. But there is just something about her, maybe she looks too similar to Elle Fanning and that bothers me.
Either way, "Split" is fine....just fine.