Fascinating little book, even almost forty (!!) years after it was published, and still relevant. The only drawback (from my perspective) is that its intended audience is Japanese who are learning to better navigate American cultural waters -- I'm sure for anyone in that group this would be a four- or five-star book. Unfortunately I am an American trying to better understand Japanese norms, and while there is definitely some valuable insight, the Japanese text and assumption a reader's first language is not English doesn't help me in particular, so three stars.
(What polite fiction would my rating system fall under? Probably "you and I are original," since the individualism of my experience takes precedence over the book's overall usefulness or objective value. Wow. Really worth reading.)
While it is written for Japanese people to better understand Americans, it works equally well for Americans trying to understand Japanese people (it's basically 3/4ths in English a 1/4th in Japanese).
It's short an succinct enough that I'd recommend it for anyone traveling to Japan for any period of time and especially if you're studying abroad there or going to work there.
The only "negative" is that it's a bit dated, but that only affects certain references. Overall, it's still applicable to Japanese culture in the 21st century.