Jo Walton is an award-winning author of, inveterate reader of, and chronic re-reader of science fiction and fantasy books. What Makes This Book So Great? is a selection of the best of her musings about her prodigious reading habit. Jo Walton's many subjects range from acknowledged classics, to guilty pleasures, to forgotten oddities and gems. Among them, the Zones of Thought novels of Vernor Vinge; the question of what genre readers mean by 'mainstream'; the under-appreciated SF adventures of C. J. Cherryh; the field's many approaches to time travel; the masterful science fiction of Samuel R. Delany; Salman Rushdie's Midnight's Children; the early Hainish novels of Ursula K. Le Guin; and a Robert A. Heinlein novel you have most certainly never read. Over 130 essays in all, What Makes This Book So Great is an immensely engaging collection of provocative, opinionated thoughts about past and present-day fantasy and science fiction, from one of our best writers.