One problem is that the book does not adequately establish the relationship between the common people and the central authority. This central authority came to be challenged, at different times, by powerful interests. There were families close to the court who schemed to influence the imperial succession. Later, there were the shoguns and the daimyos who arrogated sovereign power to themselves. But if the original relationship between the common people and the emperor is not adequately described, anything that comes after risks deteriorating to just a sequence of dynastic game-plays, and will be of little interest other than to Japanese history buffs, Japanese ultra-nationalists, or foreign Japanophiles with a habit of memorising arcane names. The coups and intrigues of the Japanese elite can only be interesting to a certain point. Of far more interest to me is the way that the lives of ordinary people were conducted. Because of this, the book is something of a failure. A well-written one, to be sure, but it falls short of my personal aspiration for knowledge.
Having mentioned Japanese ultra-nationalists, it has to be said that this book might be cause for some discomfort in that quarter. This is because the book's early chapters deal with how the Kofun people, hunter-gatherers who inhabited a wide area including the Korean peninsula and parts of Russia, were edged out of their demesnes in the archipelago by invaders from Korea. These new arrivals are called the Yayoi. They brought new technologies, including wet-rice cultivation and iron weapons. The Kofun were pushed north into the northern parts of Honshu (the main island of Japan) and into Hokkaido. Remnants of this population still exist in Hokkaido today, where they are called Ainu. For those who are interested in learning about the way the make-up of Japan's genetic pool was changed over time, the arrival of the Yayoi some time in the millennium preceding the birth of Christ must be of major interest.
This kind of knowledge is not trivial in its import. Even up to the end of WWII, Japanese school children were taught that their emperor was descended from the sun goddess, Amaterasu, who was said to have placed the royal family in a position of ascendancy over the population of the Japanese archipelago. Such myths were perpetuated after the introduction of writing (again, this happened through Korea) in about 500 AD. There is no doubt that many Japanese today will still believe them. But they are ridiculous. It might be hard for the Japanese to believe that their ancestors were raped and murdered and dispossessed of land by a more technologically-advanced race of people who arrived from the Korean peninsula, but it is without question true.
So the book is worth buying if you only intend to read about this part of Japan's prehistory. And I recommend it highly if that's your aim. For those who want to know more about how the common people of Japan - who remain largely invisible in this book - managed their daily lives while the elites plundered, robbed and taxed them, then this book might fail to provide all the information you need. But that kind of information may not even exist anywhere, I don't know. If you come across a book of that type, let me know, I want to read it.