The book lists the fly patterns by their style & each gets a section of the book:
I - Surface patterns
II - Subsurface
III - Attractor & Baitfish
IV - Color Plates
In addition there's also a section of the book that deals with fly tying materials, hooks, etc (the listings of dealers might be a bit dated).
Throughout the book historical notes are made for those fly patterns that have any historical significance. There's also some tying directions & descriptions for different aspects of fly styles. In other words, there are general explanations on how to tie wet fly hackle or dry fly wings, for example.
That said, this is NOT a book for the beginner. There aren't enough "how-to's" shown for someone just starting out in fly tying. For the beginner, I would point you in the direction of Eric Leiser's other book, "The Complete Book of Fly Tying".
These days the internet has pretty much all the fly tying patterns & info you'll ever need. But for those of you who enjoy a good, informative book - or don't always have internet access at the tying bench - this is a great book to have. With all those fly recipes listed, you're sure to expand both your knowledge of flies & your offerings to the fish.