This was one of two books highly recommended by Wendy Johnson on her knitting blog, Wendy Knits. The other one was Ann Feitelson's book on Fair Isle knitting. I also recommend anything by Alice Starmore, though some of the books are outrageously expensive due to being out of print. I've gotten some from the library, though, so that was ok.
Check out Wendy's site. It's a good one, and she's in the middle of a Fair Isle project right now.