This review contains spoilers.
Unbreakable is one of my favorite movie. This is a betrayal. Maybe I'm too inflexible and just don't accept that the movie isn't what I wanted it to be, but in this case I just don't like what it is.
The first thing I didn't like is that David Dunn plays a vigilante. One of most effective way we could identify with David Dunn in Unbreakable is that he was a level-headed and reasonable person. Sure, he did follow a villain to save the children, but he was experimenting, roaming uncertainly. He was just discovering the possibilities and limits of his powers. Watching him assuming the role of an organized vigilante as if it is his duty seems so unlike his character in the first movie. The absurdity of it becomes even more obvious when pondering over his powers. He has two powers: visions of crimes; and super-human force. Out of those two, visions are by far the most powerful. Super-human force is no match for a properly trained SWAT team, and is dirtier anyway. Visions can spare the work of months of police investigations. He could just roam the streets, follow the bad guys, and make anonymous calls to the police once knowing enough. This is what David Dunn from Unbreakable would have done anyway.
The second thing I didn't like is that the movie was way too didactic. Shyamalan did the same mistake the Wachowskis did with Matrix Reloaded: over-analyzing the base subject with monstrous verbosity in-between action scenes. Unbreakable was a masterclass of "Show, don't tell", and Glass is the exact opposite. The scene from the poster where the three characters are seated while being interviewed by the woman doctor is absolutely clumsy. It is unnecessary, it tells too much, but tells nothing useful. The doctor is trying to explore the possibility of David deducing the intentions of the bad guys he "senses" by subconscious Sherlock Holmes'-like analysis, which is irrelevant because he has VISIONS. He sees things happening in another place he never visited, and which are happening for real exactly like he sees them. The directing and editing proved it to us. What are we supposed to do as spectators? Doubt?
The third thing I didn't like is that the story goes the comic-book way. Once again, what was so great in Unbreakable is that it was super-hero story narrated in a context that was very realist, with setups and characters we could identify with. Glass, on the other hand, leverages all sorts of tropes and clichés that is typical of modern, tasteless, super-hero movies. Everything that revolves around the character of Dr. Staple, played by Sarah Paulson, suffers from this curse. She is mysterious, elegantly clothed. She doesn't feel like a real character you can identify with, she is a comic-book character. She manages a psychiatric hospital in which the three characters are gathered, in a plot mechanism that doesn't make any sense. (How ironic for Dr. Staple to explain to David's son that he was a vigilante punishing bad guys without proper judgment when David lands in this psychiatric institution apparently without any judgment.) We eventually learn that she belongs to a sort of sectarian organization which is comic-book-level conspiracy trash.
I don't understand Shyamalan's process in his trilogy. Why destroy everything that proved so effective in Unbreakable and do the exact opposite? As for the Split continuity, well, there isn't much to take from it, apart from an acting circus by James McAvoy in the scenes where he zaps from one personality to another. It has the virtue of making the movie playful, if not subtle.
Glass was a bad movie until the end, where it became a disaster. Firstly because Shyamalan pulls out a terrible twist which is based on the assumption that people in 2019 believe that videos they see on the Internet are real, and secondly because <spoiler>David Dunn is killed in a fucking puddle.</spoiler> This last bit requires me to take the drastic step of considering that Glass just didn't happen. It was a mistake, and we can all live a good life by erasing it from our brains.