Well, what can I say, out of the books trying to give a general overview of the history of Japan, this one is a good pick - albeit with a few grains of salt.
Mason and Caiger decided on a very holistic approach, meaning aside from the description of major events and historical figures they also covered cultural and societal aspects, such as theater, music and literature. Additionally they also give an overview of the major Japanese Buddhist sects; a very good idea in my opinion, since their influence on Japanese culture and politics was great. All in all, I have to say, that the depiction of Japans history and the major factors that shaped Japan as a nation, were very well selected and elaborated.
That being said, I mentioned some salt, so let's get to it. First, even though I liked the structure of this book, it was also somewhat dense. Also, they sometimes brushed over certain events in passing (like the great Kanto earthquake of 1923). I believe for people, who are not familiar with Japanese history it might be quite dry and a little overwhelming in places. This rings especially true for the chapters on the Meiji period, those were unfortunately quite compact. (I've read that Mason is an expert on the Meiji period and therefore I felt he really wanted to put in as much information as possible, which ended up a little too much).
The second grain of salt for me was the handling of the Korean occupation. It is only mentioned very briefly and there is no mention of the crimes committed by the Japanese during the second World War. In general the chapter on the Pacific war is very, very short, all things considered. I understand this book was originally written in the 70ies, but still, that was really not enough for an event of that scale.
In conclusion, unlike some others here, I didn't find this book boring at all. But I am quite enthusiastic about Japanese history and I feel it might be a little more fun to read if you already have some prior knowledge. If you only want a quick overview, you might want to look elsewhere - there are books that are more concise and up to date.