There has been much discussion about whether or not it is socially acceptable to watch Split. I'm gonna skip right over all of that and talk purely about the movie itself.
Anya Taylor-Joy is good, but McAvoy is what makes Split worthwhile. The heavily touted twist/reveal was all but a non-event, even to a M. Night alum like myself. Though it is certainly (in my opinion) the best work The Shamhammer has brought out since at least Signs, it's hard to say that its successes rest on his shoulders. Again, it is for McAvoy that we really owe praise, who, with the exception of his role as the lead in Filth, gives his career best performance.
Final rating:★★★ - I personally recommend you give it a go.