I liked some of what they did, but so much of the movie was just a series of straight-up 'take that's' at TFA and the prequels. Rey's parents? Nobodies. Luke's lightsaber? Tossed away, then broken for no good reason. From a certain point of view? Ben and Luke's different perceptions of that fateful night. Poe is a swashbuckling derring-doer and gets his whole squad killed? Fuck you, Star Wars is swashbuckling space opera, it's SUPPOSED to work like that.
My main problem with the Luke story is that it erased all of his growth from ESB and ROTJ, and turned him right back into a whiney little bitch who wanted to go to Tosche Station and pick up some power converters. They could have had him being an inscrutable old master who went into seclusion to discover where he went wrong, and figure out where to go from there, but instead, he was just running away and hiding. He should have been training Rey like an old kung-fu master, or like Yoda. Yoda's force ghost should have shown up and been like 'That bad, was I? So silly, my training techniques were?'
Having Luke's final interaction with Leia and Ben be nothing but an illusion robbed it of EVERYTHING. Luke should have shown up on the planet in person, kissed Leia, apologized for Ben, then strode out and called Ben out. The AT-ATs and what not should have been wiped away with a wave of the hand when they tried to interfere. Luke should have absolutely CLOWNED Ben, then simply turned off his lightsaber, said something like 'You see? Even though I'm far more powerful than you, I still failed. Strength alone is never enough' and Obi-Wan'd out. Rey should have been left on the Falcon, at the end, looking across all of the old Jedi texts, and one new one, written by Luke Skywalker. She should have been the inheritor of his new understanding, the one to actually put it into practice.