When I saw this movie in theaters for the first (and only) time, I immediately picked upon a major problem; it is incredibly self-indulgent in it's subversiveness, which is essentially just a nice way of saying it's unpredictable. While that's not a bad thing in itself, but when you do it at the expense of all else, including character development and storytelling, what you get is a series of twists for the sake of having them, regardless of whether they actually make any sense or not, resulting in a good chunk of the entire movie being rendered almost entirely unnecessary in retrospect. The Last Jedi feels like it just repeatedly pulls the rug from under the viewer just so it can say "gotcha!", but you know what they say; fool me once...
On hindsight, another major issue with the film is it's complete disregard to it's own legacy. I'm not even talking it's introduction of some serious issues in the rules of the entire Star Wars universe as a whole, or about turning Luke into an old, decrepit, miserable hermit (and I'm not even going to talk about what I see as blatant character assassination), but it fails to even develop the characters introduced in The Force Awakens. In fact, that's something of an understatement; the characters either don't develop at all, or they're essentially reduced to two-dimensional parodies of themselves who plod their way through the film in displays of massive incompetence and/or foolishness. I know making characters act stupid is a common storytelling device to keep the story going forward, but The Last Jedi abuses it to a nauseating degree.
Much has been said about the new characters as well, they're really not that much better off. Rose Tico in particular almost feels like a parody of a typical college liberal. Her dialogue reveals her naivety, and her actions reveal her failure to consider possible long-term harmful effects in favour of short-term "feel-good" benefits, and in one instance in particular the former kicks in almost immediately on the background after she makes some adage about it, which in any other film would come off as a biting satire - I only say she almost feels like a parody, because I'm positive it was not intentional. It merely demonstrates utter cluelessness on the behalf of Rian Johnson.
The film may be impressive visually, but the inside rings hollow. With all the characters worth caring about either dead, flat or reduced to stereotypes, there's just nothing left for me to care about in Episode IX. The franchise is clearly in the hands of people who do not care about it. I guess Rian Johnson does get the last laugh with his biggest subversion of all; the expectation that this movie might've been even remotely decent. Needless to say, I'm not going to see it. Fool me twice, shame on me.