The biggest problem with Rogue One is essentially the central problem in Lucas' prequel trilogy: the outcome is a foregone conclusion. The whole film is irrelevant. But where the prequel trilogy (which truly deserves a full-on reevaluation in light of the soulless corporate product Disney has been churning out) unfolded over a period of years, Rogue details the weeks immediately prior to the opening of A New Hope. Remember those secret plans acquired by the Rebellion which revealed the weakness of the Empire's Death Star? In Rogue One we get to see exactly how the Rebels acquired those plans. Why? Because it gives director Gareth Edwards plenty of opportunity to recreate the precise atmosphere of Lucas' original film.
There's a reason why "cut to the chase" is such a reliable, time-tested cliche. The interesting and exciting story, which Lucas understood back in 1977, is how the Rebel Alliance fought and ultimate scored a huge victory against their oppressors. The completely anti-climatic part of the story was only hinted at by Lucas: how the Rebels found the plans. Maybe it didn't have to be such a bore, but in the hands of screenwriters Chris Weitz and Tony Gilroy there's nothing compelling about this batch of characters or their mission. Rogue One plays like the adaptation of a decidedly mediocre Star Wars novel. Those Expanded Universe books and comics have ranged widely in quality over the years, but any of the best ones could've made for an interested movie. Instead, Disney decided to give us a story that really didn't need to be told.
Probably the key development in Rogue One is the violent bastardization of Lucas' entire concept for the Rebel Alliance. The Rebels of Rogue are a bunch of murderous mercenaries. Rebel Captain Cassian Andor (Diego Luna) exemplifies the Disney vision of the cutthroat Alliance, a double-crossing cad who's willing to work with Jyn Erso (Felicity Jones), a young woman whose father Galen (Mads Mikkelsen) helped the Empire develop the monumental Death Star. What Jyn doesn't know is that the Alliance has ordered a hit on her father. In an effort to up the "darkness" ante (and if there's one thing the most rabid Star Wars junkies seem to crave, it's darkness—whatever that even means), Disney has crafted a modern war movie and reoriented the Star Wars ethos.
Shame on Lucas for selling, he is to blame for the gutting of his own creation. But still, it's amazing how cynical Disney has been in their treatment of this property. Lucas reportedly "loved" Rogue One, which either says a lot about his taste... or he's lying, since he was perceived by some as a crybaby when he expressed misgivings about the The Force Awakens. Given his reaction the earlier film, I'm guessing he's simply being more guarded about his true feelings this time.
Rogue One flickers to life briefly during a couple of Darth Vader (voice by James Earl Jones) appearances, but his role is mostly like all the other direct visual and sonic tie-ins to the original film: fan service. Vader doesn't serve any real purpose in the narrative (the main villain is Grand Moff Tarkin, ostensibly played by Guy Henry but digitally altered to look like a rather silly animated version of Peter Cushing). Vader shows up because he's a cool villain and lends "authenticity" to this Star Wars Story (but all "authenticity" is shot when Vader breaks out some Dark Side tricks far beyond anything he displayed in A New Hope, which picks up literally minutes after Rogue concludes).
More than an hour's worth of featurettes are included on the second disc of Disney's Rogue One Blu-ray edition. This stuff isn't too revealing, but they do help shed some light on the creative (if you want to call it that) process of piecing together a fast-food Star Wars movie. Clearly the producers knew their mission was to serve up more of the same to the ravenous fan base.
Rogue One: A Star Wars Story is also available in a Blu-ray 3D edition.