Based on a quick perusal of the "look inside" at Amazon it seems to be reasonably well-written, and I like that it's bite-size entries with pictures. I stumbled across it while poking around games on PC-98 and similar Japanese home systems recently, I never paid much attention to them before as the language barrier is so severe, but some of the pixel art the Japanese were producing in the early 90s is just absolutely fantastic and pushes me on. It's particularly striking by comparison to the Western gaming industry's obsession with ugly early 3D in the 90s. Really two different worlds.
As for the "Untold history of Japanese Game Developers", I've run into Szczepaniak in various places over the years (he used to post on Assemblergames way back in the day... RIP), he always seemed like a natural researcher/historian and has done some great work. I did catch part of the four-hour documentary to go with "The Untold History of Japanese Game Developers"; it was woefully unfocussed and rather desperately in need of an editor, which put me off a bit. I'll have to have a look if you say they're that good, though, I had been meaning to check them out anyway.