This book is just another masterpiece from Fabien Sanglard, and a great continuation of the exploration of classic games he started with the Wolfenstein 3D book. It makes you appreciate the ingenuity of Id Software, when they had to work with limited resources, no multithreading/multitasking, limited color palette, and a fragmented landscape of audio devices. You'll also appreciate the level of details that went into the game design.
The section about various ports to a range of hardware, and the time frames it was done, is astonishing. The description of hardware capabilities, audio/video interfaces, and design decisions behind them is quite interesting, and takes you to the nostalgic mood of good times when innovations ran wild.
The most impressive message I carried out of the book is how the Id engineers cherished the concept of time. One example of that is that DOOM.EXE came with a special way to load WAD files when the file name was prepended with a tilde. That would save the game designer ~30 seconds of game initializing so he would see the results immediately. The theme of valuing time is carried throughout the book, and it's possibly that way of thinking that contributed greatly to the success of Id. The concept many modern software engineers could learn a great deal from.