I'm slightly disappointed in this book.
I paid top-dollar for it, for starters, and I only did so because everyone kept telling me it was a must-read. Sadly, it's not. I'm not saying that it's a total loss or anything but most of the information is completely out-of-date and not in sync with the new theories or better conclusions that have come about in just the last decade. It's hard for me to take him seriously when he constantly sources Turville-Petre throughout the entire text. Most of TP's work has been largely discredited since that time and it causes me to really struggle with certain areas of this book. I learned a few new things but nothing worth the amount of money I put into this book and "Under the Cloak."
Save yourself the money.
Don't worry about it.
Trust me.