Han Solo is a good character though. Leia is. Luke is hit and miss. Vader is. Obi Wan is. You can be a good character without being "developed". Jyn moves the plot along. Rey is a godhuman. Poe is a quippy Marvel guy. So is the robot. It's all so blah.
Luke is hit or miss, and he's the central character! I think Jyn is a good character; I also think Cassian is a good character. Rey is also a good character; I'm not prejudiced by her advanced force powers being shoehorned into TFA. Flynn is a good character. Dexter Jexter is not a good character; Jar Jar Binks is a horrendous character.
Maybe I am just easily pleased, or can put myself in a simpler mindset when watching a film like this, but as I said, if you're looking for strong, rounded, fully developed characters in the 21st century movie world you shouldn't go looking for them in Star Wars.
PS: If anybody is interested, Screen Junkies News have a very good video out talking about the trailers and the footage shown in them that wasn't actually in the movie. I think this hints where the reshoots altered the feel and final outcome of the movie.
For example, (and I'm just guessing here) I suspect that, originally, Krennic was a far stronger villain; the scene in the trailer between him and Vader suggests he might have been trying to play Vader and Tarkin off against one another, or trying to recruit Vader as an ally in a power struggle.
Vader was actually played by two actors in Rogue One; at first I thought that was because they needed somebody to do the lightsabre scene at the end, but why have a separate actor for that when you could hire a single actor capable of doing both? Makes me wonder that there were some Vader reshoots and the original actor wasn't available for them.
I suspect the opening Vader scene on the lava planet is a reshoot meant to depict Krennic as more simpering and slightly out of his depth. (I said in my initial review that I thought Krennic was a bit weak and peripheral for a main villain.) Or it could be the lightsabre battle at the end was the reshoot because somebody decided last minute they needed Vader to be a complete badass to give the film an epic climax. That might explain why the Leia Organa CGI looks so awful compared to the obvious care taken with Tarkin.
I will admit, that scene in the middle of the film with Galen Erso relaxing with Krennic felt an out of place to me. It was as though it was just dropped in at the last minute. It was the only scene in the film I found jarring and I wonder if it was also a reshoot.
People have complained about the scene where Jyn breaks down crying over the hologram of her father; something along the lines of there's too little emotional weight to the characters. I can't help but wonder if there was material that ended up on the cutting room floor that would have added some depth to this scene, but again I was okay with it.