What did you think of the protagonist James Mcavoy as the split personality lead?
This is the most crucial part of the movie in that one actor needs to play several characters and keep them distinct enough so these characters are believable. I would say he plays many characters well, but some not as well as others. In the movie he visits his therapist Dr. Fletcher played by Betty Buckley as multiple characters, usually either Dennis or Barry. Once he kidnaps the girls his Dennis personality takes control and pretends to be Barry to avoid criticism of the therapist. The fun part is that one of the personalities is trying to rat out the other personalities that have been behind the abduction and continued torment of the girls.
This is one of the great characters in the film in that she doesn't respond as a normal early teen girl would respond in a kidnap scenario. She is carefully measuring her options to escape and when it would make sense to act on that possibility. One of the possibilities is the time the split personality Hedwig comes to the fore, who is an 9 year old boy that Kevin was before the abuse began in his childhood. Casey figures out how to lead Hedwig to his room to try to escape.
Yes, the grandmother therapist character has the weighting of trying to understand Kevin and other split personality patients as her life-long career. She has a theory on these victims as possibly a higher form of the human brain that we see emerge later in the film. She is the key member of normalcy that Kevin interacts with and tries to keep impressing with good behavior. The kidnapping triggers his other personalities to wrestle with the morality of the kidnapping and where it is leading.
More or less it was as I expected. If you know Shylamalan's earlier film The Village, I would say that earlier film is clearly better. The reason is that you don't guess the plot twist as you might in the Split film. In the advertising, I think they lay out too many details of the protagonist, so you really don't get too surprised by his different personalities. I don't know how you would advertise it in another manner, but if you knew absolutely nothing going in, it would be a great film on split personality. The ending and side plot could have been more thoroughly developed played by the younger Casey. It would have been interesting to have seen how the 23 personalities arose in the film, which was just slightly scratched by the therapist. Maybe that would bore other viewers, but one of the reason say the Ring was so scary was how all the details of the villain get more and more twisted as the plot progresses. It increases the fear of the villain. I'm sure if you are 13, you might freak out, but his character really didn't get too much scarier over time. I think more details of his past could have heightened the final scenes much stronger.