The sequel movies were well written as single movies
VII is passable but incredibly derivative.
VIII is fine.
IX was a total joke of a movie.
Additionally, VIII and IX can't stand on their own. They're continuations, not some isolated story and don't work as one. They also, unfortunately, don't work as part of a trilogy either; VIII completely derailed almost every existing storyline without offering up anything new, and IX was painted into a corner so they ended up making up a new main storyline because there was almost nothing interesting left to resolve (and IX retconned/discarded what it needed to to attempt to work but it wasn't possible).
I'm serious when I saw this - I only bothered to watch IX because it was clear VIII fucked up the entire trajectory of any trilogy and as a writer I wanted to see how the fuck they were gonna get out of that corner. The answe is they didn't and it wasn't possible.
I think that after VIII, the smartest move would have been to just take a step back and say "this isn't a trilogy anymore", because it clearly never was in the first place, and work something else out. The problem is I think TLJ pissed off some of the main cast so much that they had no desire to sign on for anything beyond IX.