To Kill a Mockingbird is one of the greatest books of all time because it is about the importance of following your conscience even when everyone around you disagrees with you.
Go Set a Watchman is one of the worst books I've ever read because it turns that whole concept upside down in favor of getting along with the people in your town, no matter what detestable things they might be thinking or planning. Watchman is preachy for chapters at a time, and in the end, it paints Atticus Finch as a racist and not only that, but as a racist that Scout will go along with just because he's family
It sucks.