This is like a text book of origami theory - it could easily be turned into a college level math course. Chapters on model bases, folding techniques, creating additional points to work with (like how it's possible to make a spider with eight legs out of a paper with only four corners), creating textures (plates), asymmetrical designs, different design theories; each chapter has folding instructions for models that demonstrate examples of the concept just covered. Most of these models are advanced level and may take several hours to complete. One thing I learned when approaching a new model is to practice folding it multiple times on different sizes and weights of paper until you have achieved the skill to make a final version on a well-chosen piece of paper. Not every origami model is best made with "origami paper" that you buy at the craft store.
The shared knowledge of how to fold an origami model is not what this book is about - it is about the far less discussed tactics of designing origami models - how did anyone come up with those steps in the first place? There are many crease pattern diagrams, a chapter devoted to mathematical algorithms, and an extensive and valuable reference for when you become obsessed with paper folding, as you just might after reading this book. (Yes, I want to attempt the koi fish on the cover.)
I really like this book; I tend to like math and understand it, am logic-thinking, patient and analytical. I'd recommend this book to anyone along those characteristics. I'm not sure that it would interest everyone who picked it up. I've done origami as a kid, but it's not really been a huge hobby of mine - so don't be afraid to dive into it, just don't expect it to be a walk in the park, either.