Not sure why this movie is getting poor reviews overall. Critics are saying the plot twists make no sense. That everything seemed rushed and incoherent as if nothing that happens in TROS was planned from the beginning....alas if you look deeply into the last two movies, the connections are undeniable. I am not going to write a long drawn out review just defending some of the major plot points:
MAJOR SPOILERS
Ren is a Palpatine. Why is this so hard to believe? She clearly shows her connection to Darth Sidious in episode 7 (her fighting style, her anger, her fear of abandonment, the way she used dark side energy to defeat Kylo Ren in the forest).
Palpatine is alive?!? how is this possible? Well gee he only hinted at it in episode III that cheating death was very possible. Sounds like old Palps figured it out. Who was going to be the big bad? Kylo Ren? Nah, we needed Emperor Palpatine to make the connection to the beginning when he was a cunning politician to the end where he tries to seduce his granddaughter to become the new Sith lord.
Those are probably two of the most divisive things I've read. After The Last Jedi failed to progress any type of lineage to the Star Wars galaxy, I think TROS did a tremendous job tying it all back together. and yes he did use some of the Last Jedi plot points to progress this story.
The only real complaint, this movie felt rushed. A lot of the reveals were not given ample time to sink in. This is literally a 4 hour movie crammed into a 2 hour and 20 minute timeframe.