I very rarely read any gaming supplement from cover to cover, but this was one of the exceptions. I absolutely love this book. As with the IZ core book, there is brilliant side commentary and deep immersion into the setting. I love the way the geography and culture is laid out. It is exactly how I would expect Japan to be, grounded fairly well in modern as well as ancient Japanese culture.
A+ for dropping enough information to make the setting playable. And even more- dropping subtle hints for potential plots and adventure ideas. Even the document's author character is a bundle of plots. The characters in the side commentary are potential plot hooks. All of the area descriptions and cultural info is teeming with potential storylines.
I like the gear, golemmechs, and augments. I thought there could have been a lot more. I would have loved to have seen the Hindrances, Edges, Augments, Exo-Suits, robots, weapons, vehcles and golemmechs double or triple their length and variety of selection. The government agents should statted more upgraded, state of the art gear. Japan is kind of the giant robot capital of the world, after all. And the Japanese are notoriously tech-upgrade crazy.
I should mention there are a few typos here and there. I didn't write them all down, but the "salvery" on page 30. The overall awesomeness of this book far overshadows a few minor editing issues.
Interface Zero in general and this book especially capture a wide variety of staples in the cyberpunk genre. I especially like that I can replicate/emulate several anime/manga that I love. This is very Shirow-punk. Appleseed and Ghost in the Shell especially. You can also do Akira, Ghost in the Shell, Patlabor and Bubblegum Crisis. I also like that the door was opened for kaiju.
One of my mild dislikes of IZ in general is the introduction of psionics. Luckily, this book doesn't delve into a lot of that subject. The zeek population of Japan is small and well contained. Personally, in my campaign, there are no zeeks, but I don't begrudge other people needing that "magic" type element in their game. I thought the presence of hybrids, bioforms, etc bordered on going overboard, also in the medieval fantasy way, but also subject to GM editing, easily avoidable. I got a chuckle out of the knockoff Pokemon/totoro bioforms, though. (Kami-Cuties.)
The only otther addition I thought about would have been Zen archery or even Zen gunslinging. The attitude would be something to the effect of anything worth practicing is worth perfecting. The Zen Master archetype as presented is really not prone to ranged combat.
Overall, other than a little post-editing, completely amazing book. Well worth the money.
[5 of 5 Stars!]