Koren is dismayed by the erosion of the traditional Japanese aesthetic of wabi-sabi from that country's culture, and has attempted in this slim book to explain what it is. This task is slightly counter-intuitive, since it is not unconnected with Zen, which is rather against explanations.
Still, not only does Koren explain the philosophy to a more of less successful degree, including some fascinating historical footnotes, he also produces a book that seems to exhibit many of the described qualities: small, simple, unpretentious, with a lack of concern for the name of the object maker (his name does not appear on the cover), murky. And incomplete.
I feel I have probably missed much of what Koren is trying to communicate. But a few ideas do resonate. And the final paragraph is a delightful limpid summary of the tension between the desired simple and undesired simplistic.