It includes chapters both on and by several sf authors, as well as some non-genre authors, and authors who are not necessarily known as sf authors (at least they weren't to me), but who have one or more sf works. I bought it because I was particularly interested in getting started reading Sherman Alexie, and because I read Zora Neale Hurston's Their Eyes Were Watching God and then didn't know where to turn next to approach her writing. (All the authors covered int eh book are listed on their website.)
Once I started reading, I couldn't put it down. I found myself reading straight through essays on authors I'd never seriously considered reading before, as well as on authors whose work I've already thoroughly explored. I found everything insightful, interesting, sometimes amusing, and always personal and particular.
I particularly like that it might lead people who aren't sf fans to pick up some sf that they wouldn't have considered before.
Check it out.