There seems to be an endless supply of bad books written about the RasPi and unfortunately this is another one.
The guide is not comprehensive at all. A lot of the chapters read more as a sales pitch than a technical explaination. When you first receive the book you have a momentary sense of joy as you look at the thickness and feel the weight. Then you open it and realise it's written in a font so large that you'll spend as much time turning pages as actually reading them.
The worst insult of this book is how little there actually is in there. All of the information is available freely online, but worse than that, it's not even good information! Take the section on the RetroPie...There are over 2 pages listing the systems it can emulate. Then it goes on to recommend the RasPi 4 (I mean, it is in the title of the book after all!). It's just a shame that RetroPie doesn't yet support the RasPi 4 (although apparently there is an experiemental build out there somewhere). I'm not surprised that the author didn't know this though, they obviously have not tested or tried much of what they have written about.
To summarise, this book was written by a person with very little knowledge who used the internet to fill pages with sales garbage because they lacked any technical knowledge to actually add anything relevant to their book. Avoid at all costs. It is good for little more than burning on an open fire.
On a positive note, the front cover is a pretty colour :)