Split

Like all Unbreakable fans, I was excited at what Split means for the future of David Dunn, but I'm going to say right now something that might disappoint some people.  There should not be more than the one movie that Shyamalan has suggested.  Think about it.  Wouldn't this be the perfect film trilogy?  Most trilogies follow one character as they go from villain to villain, or from encounter to encounter with the same villain.  Instead, this would be an origin story for the hero, then a separate, unrelated origin story for the villain, and finally the showdown finale!  Antagonists often get the short end of the stick when it comes to development, so Split is very exciting from a big picture standpoint.
But what about as a standalone film?
Split has several things going for it, and a few things going against it.  First, there's that whole twist ending thing that is the Shyamalan staple.  There are a few twists along the way, but nothing to freak out about except perhaps the introduction of David Dunn at the end.  The main twist was that Casey is broken enough that the Beast doesn't want her, but anyone trying to understand the Beast's philosophy would know he would at least think twice about her if he knew.  The entire time, we're getting flashbacks, and so we're obviously wondering when the backstory will tie in, so it's no surprise when the Beast is ranting about only the broken being worthy, that he's going to eventually discover she's okay.  So, story-wise, there's not too many surprises, and certainly enough explanation from various characters, especial Dr. Fletcher, to make sure that even the most disengaged of viewers can follow the main idea of the DID (dissociative identity disorder) pros and cons and the various characters feelings about DID.  Its a thrilling, but not too complex, story.
The acting, on the other hand, is certainly on par with any other blockbuster.  This is, almost entirely thanks to James McAvoy.  His range is explored wonderfully, with him changing not just his voice and looks, but subtle mannerisms and posture as well with each new alter.  I enjoyed everything about his performance, and had a hard time remembering it was him at times.  The rest of the cast supported well, with the three girls avoiding some of the hamminess of your typical teen girl in a horror film.
The soundtrack was at times startling, and constantly thrilling, and the production design evoked some of the great suspense work of the past while not quite being familiar enough for me to let my guard down.  Overall, I can't say a lot of bad things about the film.
The biggest complaint I do have, is that it just didn't pull me in.  It seemed like it was trying to make more of the story than it needed.  The story really was about understanding who the Horde is.  We want to be exposed to this villain from all angles, so we see him from the psychiatrist's view, the captive's view, and from his own view.  We see his past, his present, and a glimpse of his future.  We are trying to understand his disorder and the rules it follows as well as his motivations as each alter.  Yet, for all these questions we have, most of them are answered through an explanation, not a discovery, and these explanations are interrupted by several escape attempts by the girls, most of which aren't plausible, and all of which are fruitless.  By far the most interesting thing about this film was the DID and McAvoy's portrail, so why not make your star player shine in the most exciting moments?  Nope, lets only let anything exciting happen when he's not even there.  Rather than escape attempts using coat hangers and air ducts (seriously?), lets have them try to understand the obviously messed up captor, and slowly they come to find what he wants and why, but also some of his weaknesses.  Finally they use his own disorder against him to make a bold escape attempt, but are stopped as the Beast or another personality seizes control just in time to stop them.  I'd have bought that movie.
As it is, I'm planning to wait and see if there's a 3 pack someday with Unbreakable, Split, and the third film once it comes out, and I'll buy it then.  I'll recommend watching it, especially if you liked Unbreakable, but I'm not recommending you drop $20 on the Blu-Ray just yet.  We'll have to wait and see how the sequel plays out before passing more judgement.
And speaking of Unbreakable, that's a must see, and buy if you can find it, so I have high hopes for the final film in the franchise, despite some shortcomings on the part of Split.