Luckily, I didn't have to pay $20,000 to learn about this book... but my friend did. He went in with a known producer to make an EP, and said producer told him and the band they HAD to purchase and understand the concepts in this book before they began working.
I am a firm believer in word of mouth > marketing, and this case is no different. I also believe that you can't possibly work in music, be it mixing, recording, etc and not understand music and the 'structure' that make it so. This book will help with all that.
My dream came true when I learned that Jason Blume holds seminars here in Nashville, and that they are free.... and that they are much more involved than a book, or a mus1030 sonwriting course...