Well I suppose part of the movie felt slow and uninteresting, I loved how they added a few new characters though and created more depth behind the whole ''Team that captured the blueprints from the Death Star''. Which was always kind of an ''unknown'' topic, besides that the rebellion just suddenly received them through a team.
It helps shape the star wars universe further.
Especially the ending IMO was one of the best Star Wars movie endings, the chills that I felt when I saw Vader appear was quite insane.