I really enjoyed it. I was a bit disappointed with The Force Awakens and came away from TFA feeling "Well it was better than the prequels" but I came away from Rogue One actually having genuinely enjoyed it.
It's definitely up there with the Original Trilogy and definitely the best Star Wars film since 1983. It's what I wanted from the prequels, darker, slower paced, unique characters.
There was an actor at the beginning who luckily gets shot by Cassian after a few lines, (the guy who tells him about the pilot) who's acting ability can generously be described as abysmal and i thought "oh dear, here we go...", honestly I have no idea how anyone saw that scene and thought it was a good idea to leave it in the movie. Luckily I was unfounded in my suspicion that this had set the tone for the rest of the movie.
I was not a huge fan of The Force Awakens, I actually think it's worse than the prequels on many counts but rogue one is a hundred times better than both the prequels and the force awakens. I love that the rebels are shown with more in-fighting and less organisation, I like that they blur the moral lines and it's not just "good guys vs bad guys" in places. The pace of the film seemed more like ESB and ANH which are slow in places, I think it adds some contrast to the fast-paced fight sequences. The sense of scale of the movie is incredible, the ships, cities and death star actually feel huge. I liked Tarkin but I think they could have easily cut down the number of scenes he was in and not having lost anything.
There were a few things I didn't like:
The plot makes no sense, (i only saw it once so i may have missed something that clears this up but) a couple of minor dialogue changes could fix it: Why did the rebels suddenly decide to help rogue one after they had initially decided not to? Why didn't cassian kill galen? Why do ships need to fly onto the imperial planet through that shield? Just land on the other side and fly through the atmosphere???
The robot comic relief. Although better than C3POs "this is such a drag" type puns in Attack of the clones, really added nothing to the movie and I found him annoying.
Fan service. There are times when it just screams "Hey do you remember this from the original movie??" They bring Bail Organa on screen like he's some major character we should be cheering to see, he's always been an incredibly boring minor character and he doesn't add anything in this movie. That said, I did enjoy the way they used footage of the pilots from ANH
Boring ships. None of the new ships are particularly interesting, I'd have liked to see something cool looking like the falcon (although a different ship). I half expected the imperial shuttle they stole and took back to the rebels to be shuttle tydirium, I'm not sure whether this would have been a good thing or not though but it would tie in to RotJ and "it's an older code"
Vader's helmet. Seriously what is with his fat neck?
An asian guy who of course knows martial arts? Are they trying to make it seem like the movie was filmed in 1977?
Overall though, it was the best Star Wars film we've had since RotJ and I'd love them to make more movies like this than movies like TFA which just copied ANH.