I was really blown away by how well this movie handled the protagonists. For each of the half dozen characters:
We introduce them.
We establish an endearing personal quirk.
We establish something they're good at.
They get a spotlight roll in a good 2 or 3 cool scenes where they can really shine.
They have a personal character arc.
They get a nice little heroic death.
That's pretty much the ideal for any character in any story (well, not necessarily the heroic death part), and I could probably count on one hand the number of stories in any medium I've seen that can actually deliver that for everyone. And it's even more impressive to do it with this many characters in as timely a manner as this does, to the point where I'd encourage writers to study it as a basic 101 primer for how to establish characters.
Bonus points for managing the tightrope walk of making everyone likable enough to root for, but not so endearing to get you tearing up when everyone dies at the end (and for doing the sensible thing and killing everyone's favorite character first and just rip the bandaid right off).
All and all, what it does with its characters is enough for me to more than balance out all the flaws. That said, holy @#$% were there some FLAWS.
For starters, I can't think of another movie that was so inconsistent about pronouncing its own main character's name. I swear half the cast say "Jin" and half say "Jen" and that is a weird problem for a movie to have.
Also weird, basically everything from Jyn closing that bunker hatch as a child up to... roughly the halfway point of the movie is an incoherent mess of scenes that only make sense in the context of an earlier draft where this was a movie primarily about Saw Gerrera, as opposed to one where he's... kind of this utterly redundant McGuffin-father-figure. Seriously, his only actual importance to the movie is that in the process of sending Jyn out to find her dad as an excuse to get all the characters together and get the plot rolling, finding her surrogate father seems like a promising start. Cut him completely and you lose nothing to the overall narrative. Mind, I'd like to see the cut where he actually DOES matter to the plot, getting all Apocalypse Now with his culty group and/or going full Metal Gear introducing us to more of his comrades than just Psycho Octopus.
Similarly, while it DID make a nice backdrop for introducing half the characters, I think they were way too on the nose with Space Afghanistan. After a point your drawing on people's real world understanding of what war looks like stops being an influence and starts breaking immersion (especially the tank! Things don't roll along the ground in Star Wars, they hover like meter over the ground, or they have legs), and it feels a little disrespectful too, playing things so close to current real world horrors like that.
Also for a standalone movie it... really doesn't stand alone very well. There's a serious issue of stakes, in particular. In a vacuum, the climax of the movie coming down to passing a hint on how to defeat a superweapon on to people so they can work out a way to defeat it and then just stopping the movie is... just unacceptable writing? The heroes all die without knowing if their efforts ultimately had any point at all, as an audience we don't actually get to see if they do either (and it's not even an intentionally unambiguous point, because obviously we KNOW, from external sources), and the villains aren't... particularly brought up to speed on the plot at all?
And in context, it's arguably even worse? In the context of A New Hope, all the events and sacrifice in this movie boil down to... setting up a quick infodump to set the scene for the big climax... and nobody getting that infodump really knows or cares about anyone from Rogue One at all.
There really isn't a fix for this either, it's an inherent problem baked into deciding to make this movie. You could awkwardly end it with a big "Later..." and then splice in footage from A New Hope's climax, but that doesn't work unless you establish those characters earlier here, and I don't want to stick Luke in this background side story. You can't even sell the heroes being successful by ending on the villains silently brooding about their upcoming doom because... like half an hour after the end of this movie we have them all sitting around a boardroom being all smug and self-satisfied. Which leads into another semi-inherent problem.
There really isn't a good villain in here... and it'd be hard to really have one. Vader's off the table, as is the few seconds of screentime he has are pushing things. Tarkin's better, and I'm glad they worked him in, but his whole deal is being blinded by arrogance in the next movie, so, he can't really be made aware of this sort of thing. So we've got the... evil space emperor's scary goon, checking on this trusted general, who's overseeing this newly created project manager, who in turn delegates to the main character's dad, and even THEN he's just kinda awkwardly shoehorned in for a climactic villain moment with no real connection to anything. His whole character is just kind of a piece of duct tape over a leaky pipe. Case to be made you don't NEED a villain because the Death Star's the villain, but, it doesn't actually get any comeuppance. Would be nice to have like... some bottom of the barrel storm trooper or techie or something as a proper consistent antagonist totally in on the plot but too far from power to convince anyone it was a big deal, or something.
But jumping back to the not standing alone... for a self-contained movie laser focused on expanding a backstory out of a minor detail of an info-dump in the original movie, and doing such a great job of feeling like it's specifically a part of that same world... way the hell do we have like 50 shout outs to random crap pulled from the deepest layers of Wookiepedia? Like the whole kyber crystal thing. There is a sense in teaching me the name of the Magic Space Rocks that make lightsabers work if I am playing a videogame with a crafting system, or if you are establishing some particular magic property of them that is sensible in that context, and going to be relevant to some big dramatic reveal later. Like, if there was a scene towards the end where Jyn had to jury-rig some kind of Light Exacto Knife out of her pendant to cut through something, sure, talk about them a bunch... but we're not. We're just talking about them (and namedropping Journey of the Whills and a ton of other random references to books/comics/cartoons/etc.) just... for the sake of referring to them/letting the author brag about being a superfan. And then there's stuff like Rude Man and Walrus Friend appearing for a cameo where not only do they do absolutely nothing, but forces you to imagine them having to just haul ass to the nearest ship as soon as they walk by and floor it to rush to a bar on another planet just in time to randomly screw with Luke and get maimed and like... what's the payoff for having to jump through this logical hoop again? Nothing at all?
The only random outside reference/cameo that isn't just there for the sake of being there is Bail Organa just randomly showing up for a couple lines of exposition, basically just saying "See, so that's why Leia sent a message to Obi-Wan!" but... OK that's really not a mystery that needed explaining, and also really not a character worth bringing back? He's just here to go "hey, remember the prequels? They officially happened!" but I mean... he isn't really a character in the prequels? In those he's ALSO a totally superfluous piece of glue? "Hey, so Leia must have been raised by SOMEONE on Alderaan right? Here, it's this guy!" So... all his appearances are just to remind you other movies exist and are being referenced. His name may as well be [citation].
I'd also be inclined to gripe about making the first major character in a Star Wars movie played by Chinese actor such a stereotypical blind kung-fu monk too, but the SECOND shows up like half a second later and he's as far from that as you can get. Plus I don't want to end on a gripe because, seriously, I liked the characters enough to make up for all of those gripes.
In particular, the aforementioned two characters are really great. Chirrut I appreciate the hell out of for the same reason I really like Maz- It enriches the setting to remind us that there is this whole actual religion behind the Jedi, and they're not just this secret order of magic space knights. Maz is really cool because she's clearly religious, with it having tangible effects on her life, but not being someone who ever like, trained with Yoda in a swamp or something, and Chirrut's cool because he's actually part of the clergy of that religion and still approaching it as a religion and not a means of learning telekinesis and acrobatics (although he's still pretty martial about it). I dig that in a general sense of, OK, Obi-Wan is a full on paladin, Chirrut is a cleric, Maz is just a rogue or wizard or whatever who stuck "The Force" down in the deity blank and is taking that seriously.
But then what I really love is Baze, because he's totally not a believer at all in any sort of pious sense, but... there's this whole character dynamic between these two where they're first properly introduced, with Baze just fully unloading his big @#$%ing full-auto laser machine-gun deal at everyone around Chirrut without hitting him, and this whole exchange about him doing reckless stuff like that because his faith will protect him and whether that's his faith in his religion or his faith in his big tough gun toting friend having his back. And it's nice and ambiguous as the movie goes on whether it's a case of which it is protecting him...
... but if you go back and watch the original movies, and in particular, A New Hope, that's... not really a distinction to be made there? Literally all the progress Luke makes in the original movie in understanding the force is getting it drilled into him that if you just kinda go with the flow and trust your feelings (particularly feelings of affection and concern for people you care about) the force will show you how to move to avoid getting shot and guide your aim when you shoot other stuff. So it's not unreasonable to assume that, basically, Baze is the hands down best marksman in all of Star Wars, despite his weapon of choice clearly not being designed with accuracy as a real concern (and firing it from the hip at that), thanks largely if not entirely to the power of love and friendship, which he'd totally deny and doesn't believe to exist. I dig the heck out of that. He really fills a niche a lot of established characters are on one side of or the other.
And again, it's really weird for this movie to simultaneously have that good a handle on the original movie's take on the force/such deft character establishment, while also thinking we need to talk about magic space rocks and such.