I've been struggling on rewrites for my decidedly not-fantasy novel, and it has stayed on my mind as it continues to collect dust. The writing book that got me thinking about seriously writing to start was Stephen King's On Writing, but Wonderbook, for me, really took that basic inspirational template and blew it apart into a lot of usable pieces.
From a purely reading standpoint, the book does take a fairly solid textbook form. The way it's set up, however, works for what's being presented in a really unique and necessary format. Much like the inspiration it tries to put in the writers the book is geared toward, it uses the fantasy constructs to help build out the ideas within.
The book is just valuable. I had ordered a copy to keep for myself by the time I was halfway through, but the interviews and the sidebars from authors were some of the most useful parts, and they're not only useful for those writing fantasy, but to someone like me writing a little contemporary story and struggling with a lot of different aspects of bringing his story together. It says a lot about the strength of the book on that alone, and I can only imagine it can be just as helpful to speculative-style writers.
Simply indispensable, and arguably belongs on every writer's shelf. I expected to like it simply because I like Jeff VanderMeer. I didn't expect to love it as much as I did, though.