I watched Rogue One and is probably my favorite Star Wars movie of all time.
Mind you, I am not a Star Wars fanboy so I watch the movie as they are, with no special attachment for the world and characters. The Milenium Falcon zipping around will not give me orgasm just because it's the Milenium Falcon for example.
Slightly Spoilers ahead.
What I enjoyed more on this movie is, first, it's a complete story. After so many open ended Star Wars movies, it's nice to get one which ends when the creditls roll.
But more important, the ammount of plot armor on this movie was reasonably low. It's still Hollywood standard but at least it was not 4 people diving head-first on the enemy headquarters hoping everybody will be looking to the other side. The guys had a plan, and execute the plan in a way to give them the best chance of success.
I found the Rogue One crew charismatic. No tsundere girl or scared-face ex-Stormtrooper. I wanted to give Heavy Plasma Guy a sandvich, but mostly to make this joke here.
The way it links with Eps IV is VERY nice and may make people watch it again with a renewed interested.
I'd say if you like Star Wars, go watch it, but I'm not a fan so what I know?