I finally received my copy of this book the other day! I've been skimming through it and have only just begun to read the interviews. Although each interview is fairly brief (two pages), they do offer new insights and in many cases I have never read interviews with some of these developers before.
Of course, the most striking feature of the book is its aesthetic beauty. It's a thrill to see big fold-out pages revealing the original design documents of the MD and Genesis, noting various features unique to each region. (One tiny detail that jumped out at me is on the design document for the Japanese Mega Drive, the Sega logo on the blueprint paper itself is the retro Sega logo from the 1950s.) It's also very interesting to see some of the box art with all of the text and logos removed, just to see the original paintings stand on their own and to learn the names of the artists. Never fear, though, because the logos themselves have their own section of the book to stand alone. There are also dozens and dozens of pages of selected sprites from many games to check out.
First impression - it's a beautiful book that I expect will reward repeated examination even after having read through it.