What Makes This Book So Great is a compendium of blog posts about Jo Walton’s rereads of books, not necessarily all science fiction and fantasy. These are blog posts originally published on Tor.com, so they are short, breezy, and quick to read. Walton is such a prodigious reader, averaging a book or more a day (I wonder that she finds time to write!). She shares many interesting insights into the whole act of reading, as well as the genres of science fiction and fantasy. Particularly enlightening for me was the idea that people who grow up reading science fiction and fantasy have internalized over time the special rules of the genre, while primarily mainstream writers may feel at sea when they try these genres; the flip side is authors who try writing genre who haven’t read a lot of it, and fail miserably. All of this content is available free online if you want to hunt it down, but it’s handy to have it in book form, and it’s of special interest to anyone who loves reading, whatever they may read. She’s certainly convinced me that rereading your favorites (and not-so-favorites) is worthwhile.