I thought it was pretty good after a slow build during the first half of the film. I much preferred TFA, but I did appreciate the darker tone of the story.
But since we like to gripe around these parts: Considering the rebels managed to get away with the plans for the Death Star, and that it is made plainly obvious to the Empire that a fatal flaw was engineered into said Death Star (Jyn told Krennic exactly that), you'd think that the Empire, with it's vast resources, would run a pretty thorough security of audit of their planet killer. I'd previously assumed that the plans were stolen without the Empire's knowledge so that there would be no opportunity to address the Death Star's fatal flaw.
Jyn did tell Krennic, but Krennic got shot and killed by the eventual Death Star blast. You could argue that the DS was built in a very certain way (which is why the father wanted to build it himself) which couldn't be simply altered even if they did discover it's own weakness, hence Vader and the Empie being so desprete to obtain those plans and prevent the rebels from discovering said weakness.
Remember Jyn's father wanted to make himself "indispensable" being the only one to build the DS himself so he could purposely input a huge weakness. As he said himself it was a matter of time before it was eventually built anyway, but this way he could input a weakness that was devastating, and clearly they didn't think an attack would have been effetive even if they did discover a weakness. In a New Hope they discuss the Rebels acquiring the plans and discovering a weakness, which "an attack on this battle station would be a useless gesture, no matter the the technical data they've obtained".