The book was about general capacities of WebGL filtered through deprecated functionality of three.js filtered through an odd wrapper of three.js in the author's sim.js framework. That said, I probably read this 5 years late. It did a good job of walking through what is possible, but it's probably better to thoroughly read the three.js resources themselves at this point.
Old book for these days, the syntax of code is changed form 2012. I would to highlight that the basic of 3D is explained. I would recommend it if you beginner but if you have other modern choice go for it
A broad rather than deep book, it's meant for a beginner both to computer graphics and to WebGL.
The only thing I didn't like about this book was the Sim.JS framework the author came up with to simplify Three.js development. Besides being oddly class-based, I found that it obscured important details that beginners should be learning by rote practice. I used it for a few projects and then abandoned it.
Clear explanation and step-by-step instructions in using WebGL for web page. Source codes are updated and available in Github. Good to know some basic HTML, CSS before reading.