There will be no clear and concise conclusion drawn as a whole by the fanbase on this movie. Those who have written off the Sequel Trilogy will nitpick it to death even if it turns out to be an excellent film. Those who love the Sequel Trilogy and can't find any faults (of which there are many, but ignorance is bliss I suppose) with it will love the film no matter what.
I can only hope that whatever potential backlash there is toward this movie isn't as outrageous as Episode VIII's was. Honestly, the people who were offended by the film have only themselves to blame for hyping it up. I've been skeptical of all four of the current Disney Star Wars films and have been either pleasantly surprised or blown away depending on which one we're talking about. To quote Tobias Beckett: "There's a lesson to be learned here."
No matter the response, I am a firm believer that
Despite its faults, Episode VIII set up IX to be potentially the best Star Wars film of all time. Kylo is (hopefully) doing his own, new thing with the First Order, the Resistance is broken more than the Rebel Alliance ever was, which means new and interesting allies could be brought into the fray, along with some old favorites.
Another good thing about VIII (and to a lesser extent VII), despite it's flaws, is that most of the plot points from Episodes IV-VI have been rehashed already. The only thing left for them to repeat is a final confrontation between our heroes and villains (which is of course happening again, but it's the end of the trilogy, so you can't necessarily complain about that being a repeat) and the "technology is defeated by nature" allegory.
The Jabba's Palace plot point was sort of combined with Cloud City for the Canto Bight sequence in TLJ, and of course the throne room showdown has already happened. Having Ren and Rey duke it out in another throne room in IX would be stupidly repetitive, and I don't think they're going to go there. I doubt there's going to be a Starkiller Base II for them to have to blow up, if anything, it might be the Resistance laying siege to the First Order's capital, or vice versa. There might be some infiltration shenanigans, but that happens often enough in both the films and TV shows, you can't say they're redoing a plotpoint from VI with that.
The only thing I'm really worried about is the "nature vs. technology" allegory. We've seen that twice in the films with the Gungans and Ewoks book ending the original six films, so we certainly don't need to see it again. If anything, Rey might use the Force to turn the tide of battle instead of simply defeating Ren with a lightsaber, which would sorta be that, but it's different enough I'll accept it.
When Episode IX comes out, it's going to be interesting to see how well the trilogy as a whole turns out. It's clear they had no plan since they allowed Rian Johnson to throw out whatever treatments JJ and crew had for VIII and IX. If they had a plan, they probably wouldn't have let him just throw out their treatments (unless his was waaaaaay better than whatever they had). Hopefully they'll nail the landing, and I have faith that they will. No matter what happens though, it'll still probably be a lesson on "How Not to Make a Movie Trilogy When You KNOW It's Going to be a Trilogy".