This is the first edition, which covers some 3000 titles. To the dedicated SF fan, much of this material is very familiar, as he covers a lot of well-known books and top authors in the field (I suspect there may be some hidden treasures yet to be discovered, but that's just my supposition). I haven't read much SF lately, and I was familiar with many of the books he reviews and rates. I would also quibble with the fact that this guide is arranged alphabetically by book title, making it somewhat difficult to gauge the worth of a particular author as a whole (and the path of his/her career) without going back and forth between the main text and the author index. Still, it is a handy and well-informed guide for the genre.