There have been reviews, positive and critical (or even scathing), for this book. I haven't finished it, and chance is never, but I do have a good guess what are its main takeaways. I think I shall write more thoughts to this review once I decided to give the book a thorough read.
Anyway, there are 3 things I can say from my first skimming, cursory read.
One is, this book isn't a serious, contemplative book. It mostly tries to impress you about Japan more so than it tries to analyze the country. You can see from the author's tone which tries to exude the impression of how incredible Japan is, in the same way a TV program showcases a country with exaggerated sound effects, and the way the book presents his experience in Japan can be likened to one TV program itself. And the cases and details as to what make Japan that great of a country are mostly anecdotal. For a personal book it's acceptable to be anecdotal of course, but what makes this a problem is the seeming lack of authenticity the author has.
Which leads to the 2nd issue, of whether the author is truly authentic in what he has to say about Japan. Perhaps he truly does, and the lack of critical things to say is just a matter of omission of things that merit no mention. I for one doubt that, however.
Perhaps due to lack of recognization of the nature of the book - which is written for the sake of adulation more than giving prescriptions to any social ill back home - several reviews have taken the book serious enough (check the references on the wikipedia page of this book). One scathing review of this book thinks he's being true to his feelings.
The third issue, which is perhaps the most notable one, is: his takes on things are very superficial, perhaps on a pop-culture level of understanding.
His descriptions on what life in Japan is like are fascinating, insightful they are not.
I'm speaking this as an (East) Asian - Vietnamese myself. This isn't to chide the author for not truly getting what those Asian things actually are like, but to say _he doesn't even try to bother to learn or study the things he (pretends to) praise_.
Or bluntly speaking, he makes up explanations without even trying to seek them.
I'm fine with people trying to understand a foreign culture but have misunderstandings of course - this happens all the times. But dropping fancy references like "Asian values", "Confucianism", "Lee Kuan Yew", etc.. when you don't have a barely decent grasp on those things?
His take on the legend of Confucius - being a wise sage that preaches wise doctrines in some book and people in Asia just immediately practice his teachings as they read it - is weird. Since I don't have a good grasp on Confucianism's history myself, I can't really criticize the author's take. Still, being somehow who lives in the culture, I can say that's not how it works, or at least whatever the impressions the author seems to make readers conjure with his words (as if Confucius is ground-breaking for coming up with the ideas of filial or whatnot, but like I said I'm really flimsy on the history myself, so let me digress).
Some of the references are not truly of merit due to its lack of relevance to the subject matter of the book (Japan). I can imagine Japanese readers get weirded out when he mentions "Lee Kuan Yew" or "Mahbubani" [1] - how are they any related to Japanese culture at all? Not directly of course, but indirectly they espouse a common Asian cultural framework and its uniqueness that exists all across East Asia. Thus you may find the offhand references to those Singaporeans to be very relevant, if he's trying to talk about Asian culture as a whole with Japan as a notable representative.
But the thing is, he even admits himself of ignorance, for not seeing how Asia can have a single cultural unity! As the continent is so huge. This is not even hard to resolve, you just need to demarcate countries in the region that share the same cultural root of Confucianism... Oh wait! There's already a label for it, it's called East Asia!
This is not exactly a guy you would trust to explain to you what are the dominant strains in (East) Asian culture that spread all across the region, before you even want to listen to him tie them up to the further ideas of "Asian values" or "Confucianism". I mean do you wanna hear an Asian explaining Western culture without knowing whether the U.S and U.K share the same country or not?
[1] To be fair, the author isn't the only one who is guilty of talking about Asian culture as a whole, despite the lack of knowledge or background to espouse. Mahbubani too. The author may have been confused due to seeing Mahbubani speaking on behalf of Asia, and Mahbubani is an Indian Singaporean. As much as the proximity which may or may not give him better knowledge, I would not put India in the same basket of Japan, China, and Korea. Nor would I put Mahbubani's words on the same plate with Lee Kuan Yew's, latter are more important to be clear.
Perhaps I shall modify the review at some point. See you by then.