What makes a book good?

I’m currently reading a mystery about authors by arguably one of the most well-known novelists in the world, J.K. Rowling, writing as Robert Galbraith. I’m finding Rowling’s commentary about the publishing industry, about writers and writing, an interesting subtext to the story, given her unique perspective in that regard. One fictional author is successful and another isn’t, one is considered “good” and the other “bad;” a romance writer’s work is described as “pornography” dressing up as histor...