Wow, how did this terrible storyline make it all the way through production? It has very good acting and some of the best CGI I've ever seen, but the entire plot is just terrible. (SPOILERS AHEAD)
The whole movie is full of amazing ideas that were developed extremely poorly. The return of Emperor Palpatine is actually something I think should've happened in movie 8 to do it justice. Instead, all we get is the incredibly lame "Somehow, Palpatine returned." Then there's Rey and Kylo's Diad connection. This is also a brilliant idea (especially when tied in with Palpatine's return to power) that was ruined by the idiotic ending of them falling in love. The idea of the bad guy in a film turning good at the and falling in love with the hero is an overdone cliche in movie-making that was somehow worse than normal. Rey's force healing ability is also a little milked, given how it's not a new concept. Obi-Wan literally used it on Luke in episode 4 and no one made a big deal. Then we have the Knights of Ren; they were a good idea, but a little over-dramatized for how lame they were. They were introduced as an extremely powerful enemy, but they basically only saw action on screen for one scene, where they all died. There are several other smaller problems with the movie, but my biggest issue with it is the final battle. The filmmakers apparently couldn't come up with any other way to destroy the Final Order than shutting down navigation and shooting their city-sized death canons with puny homemade starships. Then, when Palpatine goes to fight Rey, she kills him in seconds by holding two lightsabers against his lighting. The least the writers could've done was have some form of battle instead of Rey being "all the Jedi".
It was a lame conclusion to the single greatest universe of all time. If you want quality Star Wars content, watch The Mandalorian and read the lore, you won't regret it