Joanna Kavenna writes beautifully about both, with an eye for minute detail that makes me sure she's a huge fan. She notices how artistically Banville writes in his books, while Black's are more detective noir. She makes a case for the disparity, but just when you settle in and agree, she does a 180 and shows how similar the works actually are. References to phrases and signature motifs are key, and as she interviews Banville at the same time, giving a wide-scope picture of what might have seemed a narrow topic.
For fans of either, it's a great exploration of writer's craft and intention.