I do wonder what could have been if JJ had control of Last Jedi, would he have had to spend so much time fixing what went wrong in the past movie. That said, it was action-packed and had a lot of great cameos, from John Williams to Wedge to Admiral Ackbar's son.
I screamed when I saw Wedge, nearly cried when Chewie finally got his medal.
Imagine the set up JJ could have done for Palpy's return had he done TLJ. That's the biggest flaw of RoS, first line of the crawl and Palpy's back! Rather abrupt, but they had to get right into it, didn't they?
So much fixing, so much awesome course correction. I could make a lengthy list. TLJ was the only SW movie I've only seen once and I feel after watching RoS I don't have to.
Do I have to put Han's cameo in spoiler? It was amazing Harrison's part didn't get out before the movie. Seeing him, and that scene, was one of the absolute best moments of the film. Ben even called him Dad...