The first half of the book is related only marginally to the purported topic of the book. Here the author discusses Baroque keyboard instruments, Baroque tuning systems, Baroque musical forms, and Bach's pedagogical technique, with only occasional allusion to the Well-Tempered Clavier.
The second half of the book is more in line with what I expected. This is where the author analyzes each movement one by one. However, he does not hit every section of every fugue. I was disappointed with the discussion of the f minor and A major fugues in Book I and the G major and g minor fugues in Book II.
Moreover, the author uses several terms which he does not define. I don't understand the terms rhetoric, verset, galant, stile antico, empfindsam, monochord, Gedackt, and Pythagorean third, so I guess I'm not good enough to join the author's club.