I read this book, I enjoyed it and learned a lot. It isn't textbook quality, but I don't think it's aiming to be. I read it not to develop cryptographic protocols, but to be able to use existing ones more confidently.

It seems designed for the kind of person who isn't comfortable using something until they understand how it works under-the-hood, but doesn't actually need to do any under-the-hood work.

It assumes very little knowledge, and is light on math. Sometimes it's a little TOO light on math, and it left me confused because I was trying to understand a primitive more rigorously than the book could support.

Looks like you can read the book for free on that page if you scroll to the table of contents at the bottom.