There are many things that it does right. It certainly puts the battle between the Rebellion and the Empire into a different light, definitely showing the desperation of the Rebel Forces. It illuminates some elements of the earlier movies that had been bothering me. It serves as an effective bridge between the prequels and the originals. It also managed to bring in characters from the other movies in interesting ways.
However, there are a few things that fall a bit flat. The biggest one is the musical score. Without John Williams at the helm, the movie just feels ... different. Worse, there were times that parts of the earlier movies' music would begin to rise only to be followed by a new interpretation that ... well ... sounded like someone had made a mistake. There was no opening scrawl. Sure, this isn't one of the numbered movies, but even all of the video games have had an opening scrawl; it's part of what makes Star Wars, Star Wars. The movie is certainly dark. Sure, Revenge of the Sith is probably the darkest of the Star Wars movies if total body count and the massacre of Jedi children is taken into account, but somehow this movie felt grittier. I cannot begin to imagine how much darker it was before the Disney executives required the reshooting of 40% of the movie. Lastly, some of the CGI, especially when dealing with human faces, was noticeably warped, almost like a funhouse mirror. It was enough to crack my suspension of disbelief in a few scenes.
Still, it was a movie that I would be willing to see again. I liked the characters, felt the story was well-constructed, and appreciated it as a prequel more than any of the others that came before it. It is certainly a good movie for Star Wars fans. That said, I wouldn't recommend it to everyone.