I don't know if this book will help people be better writers. However, I do think it will encourage people to slow down a bit when reading literary classics, and to pay attention to more than just their plots.
It is true that Prose doesn't really talk much about genre fiction (except for a couple of references to Raymond Chandler) but I think that's fine. She writes what she knows, and there are plenty of other studies of what makes genre fiction great.
Paperback, 320 pages
Published April 10, 2007 by Harper Perennial.