This movie can best be described as a brain dump of Francis Ford Coppola's thoughts about society, and the trajectory we should strive to push it towards. Adam Driver in this movie is essentially just a mouthpiece for Coppola to "educate" the viewer about the world we live in and how we can make it better.
The issue with the movie is that it has zero narrative cohesion. As I walked out of the theater, I listened to multiple individuals attempt to describe the plot or point of the movie, and not a single comprehensible sentence was spoken. The best way I can describe this film is one half being a collection of scenes shown from the perspective of a paranoid schizophrenic, and the other half being spoon-fed obvious tropes and political messaging.
The movie is so abstract, and while I'm sure Coppolla could explain the context and purpose of every schizo scene (which adds up to over half of the film), there is absolutely zero context left behind for why it was there in the first place, with no room to allow for interpretation. It felt as if a majority of the subplots and scenes were added to the movie just for the hell of it.
My other gripe with this movie is that when it is not putting the viewer on an overstimulating acid-trip, it attempts to push what I can best describe as an endorsement of some form of communistic society. Maybe I am just misunderstanding the film, but from what I've gathered from watching the movie as well as from other reviews, Coppola is essentially saying that society would be better than it is right now if we put "visionaries" in power who want to create utopias. If we were to put individuals in power who actually cared about "the people", rather than those who want to maintain the corrupt status quo, then we can eliminate all of the problems in the world. If this is truly the central point of the film (which is hard to decipher due to the cryptic nature of the movie), then Coppola may just be the biggest imbecile to ever direct movies, and should be revoked of all previous accolades obtained from his past movies.
To summarize, this movie is the typical end result you get when an individual gets told by too many people how special they are. Once that individuals ego gets stroked enough, they often form some sort of god complex and view themselves as a prophet who knows better than the peons beneath him. Thus, he must put his brilliance out to display for the entire world. That movie is Megalopolis.