I would point out that the "Mary Sue" problem is basically a The Force Awakens issue.  In The Last Jedi, Luke tells Rey to buzz off, causing her to immediately fail her primary mission of bringing Luke back.  Luke doesn't like her and neither do the Jedi nun thingies.  She has a lightsaber accident.  She spends much of the movie being manipulated by Snoke.  She seeks answers within the Dark Side.  She is alternatively toyed with and rag-dolled by Snoke when they meet.  She has to be saved by Ben.  Her hope that Ben can be saved is spurned.  We learn that she's been lying to herself about her parents her entire life.

Basically, Rey had a crappy movie for herself.  The only things she really accomplishes are putting Luke in a mindset where Yoda could knock some sense into him and swooping in at the last minute to save a vestige of the Resistance.  Literally a small enough group that they could comfortably fit on the Millennium Falcon.  The overpowered Rey issues are leftovers from the incompetence of Abrams and not nearly as bad this time.  I think her biggest Force accomplishment was moving the rocks.

To give you an overview without spoiling anything.

Are you a Star Wars fan or someone who just wants to see a good movie?  If you are a fan and know the history a bit, then you will probably hate this movie.  If you are looking for a good movie then personally I would still avoid it, but I know non Star Wars fans that didn't hate it.

Are you a SJW?  If so then you will like this movie.  If not then you won't.

Do you like plot holes that are so large that you could drive a truck through them?  If so then this movie may be for you.

Do you like diversity just for the sake of diversity, even if it greatly hurts a movie?

Do you want fully flushed out characters?  If so then you probably want to avoid this movie

Do you think all straight white men are either evil or stupid?  This kind of goes with the entire SJW question, but it is apparent in this movie so much that it needs to be asked again?  If you do hate these types of men then you may like this movie.   

I suspect that you don't fall in to the categories above as most people don't, and thus the giant fall in ticket sales. 

THANKYOU! Lucas approved everything in the EU as canon so long as it didn't conflict with the main films and videogames made by Lucasarts. He didn't want to bother with making his new prequels line up with EU content, so he basically retconned everything the EU ever did. 

There's two Star Wars mythos out there. 

The original trilogy with the EU material, (that doesn't reference the prequels), intact. 

The original trilogy with bad prequels, and sequels, and all the EU content that bounces off the prequels and sequels. 

One is excellent Science Fiction in the vein of late 70's and early 80's. 

The other is just bad fan fiction. 

Oh, and this sort of thing isn't just something done by Star Wars. As an IP loses popularity, and as the original creators lose their knack for excellence (or pass the torch to less skilled creators), the quality goes down . Bendis has taken X-Men and thrown it for an infinitely complicated loop with endless time travel nonsense, that he has yet to wrap up. Final Fantasy is nothing like the 90's games. Dragonball Super, and GT went on to give the same treatment to DB and DBZ. Call of Duty is now a joke, compared to the first Modern Warfare games. 

As a franchise or IP ages it becomes worse due to additional content being unnecessary, and corporate greed. Star Wars stopped being good around the turn of the century. I'd say KotOR was the last good Star Wars content. 

I would point out that the "Mary Sue" problem is basically a The Force Awakens issue.  In The Last Jedi, Luke tells Rey to buzz off, causing her to immediately fail her primary mission of bringing Luke back.  Luke doesn't like her and neither do the Jedi nun thingies.  She has a lightsaber accident.  She spends much of the movie being manipulated by Snoke.  She seeks answers within the Dark Side.  She is alternatively toyed with and rag-dolled by Snoke when they meet.  She has to be saved by Ben.  Her hope that Ben can be saved is spurned.  We learn that she's been lying to herself about her parents her entire life.

Basically, Rey had a crappy movie for herself.  The only things she really accomplishes are putting Luke in a mindset where Yoda could knock some sense into him and swooping in at the last minute to save a vestige of the Resistance.  Literally a small enough group that they could comfortably fit on the Millennium Falcon.  The overpowered Rey issues are leftovers from the incompetence of Abrams and not nearly as bad this time.  I think her biggest Force accomplishment was moving the rocks.

In TLJ, she defeat Kylo Ren once more, she even saves his life against Snoke's guard, she saves the rebellion at the end coming the millenium and opening the escape road and she defeat Luke Skywalker in 5 seconds on the island.

Granted, Snoke toy with her easily. Snoke was overly cheated but Rey is still way too powerful, much more than Kylo Ren.

One of the most heated threads I've seen in vgchartz.