The book is a monument of literature. Its title is the genesis of your buzzy cliché, not a lazy user of it. It deserves none of that opprobrium from someone who hasn't read it.
It's not, actually. The progenitor of such titles is "Zen in the Art of Archery",[1] which was published 26 years earlier.
[1] - https://en.wikipedia.org/wiki/Zen_in_the_Art_of_Archery
Pirsig's novel references this because large sections of the book deal with the inability to express something on a purely 'classical' or intellectual level, the inability to define certain concepts, and the attempt to somehow bridge that intellectual leap of faith and explain things that cannot be explained directly.
So he tries to convey his ideas on a more intuitive level, using all the arts of redeemed sophistry through the means of creative writing, a story about travelling on a motorcycle with his son and discussing motorcycle maintenance.
It's interesting to me to what extent the huge amount of "Zen and the Art of.." books that exist these days are references to Pirsig's novel or to Herrigel's. My feeling is generally a lot of them are unaware of the existence of Herrigel's novel and the choice of phrasing does suggest Pirsig's. However, even right at the start Herrigel's title was a template for other books: only a few years after its publication his wife Gustie also published a book called 'Zen in the Art of Flower Arrangement' with a similar treatment of Zen through the medium of Ikebana or flower arrangement.
The more significant point, about the outright absurdity of interpreting Plato as a practitioner of zen--stands.
It also stands, as I said, that this absurdity makes me want to read the book--it indicates someone is following quite a different set of rules--playing quite a different game.
You're are most definitely correct on calling me out--my comment was a tad irrelevant and unfair--juvenile. Occasionally one regrets a comment after positing--one gets the sense a gut response--a passion, was at root--that comment was my gut response to the Plato/zen idea--which is a nullity to me!
At the same time I do think it's a bit extreme to call my comment an opprobrium.
It doesn't help that, as someone above pointed out, this reviewer clearly wrote the review for those already somewhat familiar with the book. Having not read it, I don't think I could give you a one sentence synopsis about the subject matter with full confidence based on that review alone. I only have that first quote from the text--which out of context, at least, seems absurd in its relating zen and western thought (though it has a fine understanding of Aristotle)
I don't think there is a one sentence description. It's a very, very rich book - a rare thing, with no easy summary possible. I have no philosophy training so I'm not qualified to discuss whether those aspects of the book make sense or not, but there is an involved (and unresolved) discussion on the nature of 'quality' which is alone worth reading it for. There is a narrative. There are questions of mental illness, of family, of interpersonal relationships, all of which are a pleasure to immerse oneself in. It is a difficult book, but ultimately I felt myself the better for expending the effort. I think you might find the experience worthwhile too, given what your comments suggest about the perspective you'd read it through. You might not agree with it but you may enjoy the argument.
A good weekend to you!