The whole bomber scene, while visually cool, made no sense. Given we've already seen Y-Wings and B-Wings serve as bombers, not sure why you need big lumbering WW2 style bombers.
The hyperspace tracking nonsense existed solely to give Finn and Rose something to do.
The whole "First Order can't catch the rebel fleet" but yet remained the same distance the entire time made no sense. If Kylo Ren and two Tie Fighters can take out the hanger and bridge, why couldn't a swarm of them take out the engines. That they are playing chase for the whole movie and just happen upon a planet with an old rebel base was just lazy writing.
Leia doing a Mary Poppins back into the ship was dumb as all hell. Given that Carrie Fisher passed, would have been a gutsy move to kill Leia then and there.
Ackbar's death. WTF.
Poe is no Wedge Antilles.
The whole Canto Bight sequence reminded me of the prequels. Aimless scenes trying to provide political commentary, with CGI overkill.
The DJ and Holdo characters added nothing. I suppose there was supposed to be tension around their loyalties, which was done far better with Lando in ESB.
They make the First Order officers comic relief buffoons. The imperial officers in the OT were far more menacing. Admiral Piett was a great villain - opportunistic, competent and believable as part of a galaxy conquering and oppressive military machine.
Which brings me to Rose and Finn. I know they exist to give a grunt level view in a universe of legends, but again the OT and even R1 did a better job of this. All the Rebel pilots killed in the OT, and the characters of R1, are more memorable than Rose or Finn. Which is a shame, because they were both good actors and their characters have potential.
Phasma went out like Boba Fett, which kind of makes sense. Cool looking character that writers don't know what to do with.
Hyperspace kamikazee? Sounds like a good idea but fundamentally breaks Star Wars. Why not hyperspace kamikazee droid piloted ships through the Death Star?
Force projection Luke was a wasted opportunity, especially since they took the time to show his X-wing preserved underwater. Should have had Luke fly in, take out a few walkers and then go all Ben Kenobi and force ghost in a duel with Kylo.
How the hell did Rey get on the Falcon after escaping Kylo?
The only redeeming part of the whole movie is the tension between Rey and Kylo. I really like how they played with the idea of Rey naively seeking the dark side and it not holding any answers for her. They nailed the throne room scene and Kylo killing Snoke genuinely surprised me. I also like that Kylo didn't necessarily turn to the dark side, and that he has a legitimate beef with the past and his goal is to eradicate it and create balance, similiar to Vader at the end of ESB.
The Maz scene was awesome too.
Here is what I would have done. Same opening. Rebel fleet escaping, but have fighters provide delay cover. You can still have Rose's sister as a pilot, maybe she kamikazees into the dreadnaught cannon like the A-wing pilot in ROTJ, allowing the fleet to escape.
Rebel fleet jumps to Crait. First Order does not follow. Base is in disrepair. Rose feels guilt and sorrow over her sister's death, wants to be more active. Base needs parts to restore shield. Finn and Rose get sent to get parts, maybe Leia sends them to Lando, who once again is a player on the fringes of the Star Wars galaxy.
Finn and Rose get to see the unseen hand of profiteers in the war, maybe a First Order agent finds them or puts tracking device on their ship. They encourage Lando to pull together friendlies to the Resistance.
Retain all the Luke, Rey and Kylo scenes. Make it more like ESB, with Rey going off to face Kylo alone. Keep the Yoda scene but add Ewan Obi-Wan as well.
They return to Crait. First Order tracks and jumps in. Ground assault to take out base.
First Order is about to win. Luke jumps in with X-Wing, takes out a few walkers, gets shot down. Faces Kylo in combat. Does the Obi-Wan sacrifice.
In the ensuing chaos, remaining Rebels board the Falcon. Rendezvous with Lando, who is waiting with a fleet of ships and fighters, do a fly over like end of ESB with fleet flying off.
Cut to little boy who is watching the fleet depart, is wearing an Alliance ring.