I mean.. Being objective not much has happen really. I think the most critical thing this movies have miss is that any of the other Lucas episodes are auto conclusive (There is the big Skywalker arc, but all the elements started in each movie have a resolve by the end of the film. The only big cliffhanger in the saga I can think was when Han was frozen in carbonite). Of course there are elements that, lets say, begin to watch the saga from episode II, you're going to miss, but the conflict itself that drives the narrative of that movie is always resolve (The killing attempt of Amidala, The mistery of the Clones and so on)

This is why Episode 7 and 8 fail so much as a movie (I'm even amaze that J.J. After dealing with this 'Mystery' box issue of his work in the Star Trek movies, opened so many plot holes in what should have been his most important film). These movies tried to be like a single movie of 3 parts instead of 3 movies with the same arc (But independent conflicts), and this is not necessarily why the movies fails, but because the mysteries of the movies 'seems' not to be that much interesting like to need that much runtime (And I'm saying 'seems' as two movies after we still don't have a clue of anything, and everything we now of 9 tell us it will prioritize fan-service instead of resolving the many holes in the script started before)