Things I liked about Rogue One:
Tone: I LOVED the tone. I loved how dark and depressing it was. I loved that all of the main characters die. (I told you there were spoilers.) This movie captured the tone that the prequels should have had. We all knew from the beginning that the prequels were not going to end well, but Lucas refused to commit to the Dark Side because they don't sell as many toys or cartoons. Disney went there because Disney embraces it's Dark Side (see Bambi), and it's still selling toys. I would not bring young'ins to this movie though. The kid in front of us cried.
Darth Vader as a bad ass: We need more scenes of Darth Vader kicking butt in the Star Wars cannon. I'd see this movie again just for the scene at the end where Vader takes out the rebels on the ship.
Mads Mikkelsen: Because he's awesome even if he will always be Le Chiffre.
Jimmy Smits: Because I was not expecting him, and it was a good way to bridge the gap between the prequels and the original trilogy.
I feel like I should have more, but really I just have a generalized feeling of having enjoyed the film. As is often the case, it's easier to elaborate on the things I didn't like.
My issues with Rogue One:
Messy Plot: The plot was messy. Why exactly was it so important to tell the rebel fleet to attack the gate, when they were attacking the gate already? This movie would have been better if the team had had a clear objective from the beginning. You are on an impossible mission to get the Death Star plans. Good luck. Instead it was go to Jedha to this thing, go to Eadu to do this other thing, go to Scarif to do one last thing. This movie could have been The Guns of Navarone or The Dirty Dozen. But that would have required the movie to take its time and build character instead of jumping right into action sequences.
Computer Animated Characters: The computer animated Tarkin and Leia were creepy. Especially Tarkin. That whole first scene with him, I was so distracted I missed any and all content. Computer animation has come a long way, but they still looked fake and... well... creepy. Peter Cushing has been dead for over 20 years. It was jarring.
Gender Balance: Or lack thereof. Having a female lead does not mean you don't have to hire any other women. This is a man-heavy movie. Aliens was more gender balanced, and that movie is 30 years old. There really weren't any women soldiers in the rebel infantry? Really? Another woman on the core team would have been nice too.
Forrest Whitaker: Completely wasted in this movie. Whey did he stay behind to die? That was completely unmotivated, as was most everything about his character.
I still liked it though. The cameos and use of the old pilots were well done. It was better than the prequels, but so was most every movie ever made.