Mathematicians are the snarkiest beasts....

Peter Woit points to a classic book review by Robert Langlands in the American Mathematical Society Bulletin that starts

This is a shallow book on deep matters, about which the author knows next to nothing.

Perhaps only second to the infamous (see the comments at Not Even Wrong)

This paper fills a much needed gap in the literature.

And goes picks up speed from there, concluding with

The book is wretched; there is no group of readers, young or old, lay or professional, to whom I would care to recommend it. Nonetheless, there are several encomiums on the dust-jacket: from Edward Witten, the dean of string theorists, and from a number of authors of what appear to be popularizations of mathematics. They are all of the contrary opinion; they find that it is “written with grace and charm”, “readable and entertaining”, and so on. Perhaps the book is a hoax, written to expose the vanity of physicists, the fatuity of vulgarizers, the illiteracy of publishers, and the pedantry of at least one priggish mathematician. Would that this were so, for it is certainly thoroughly dishonest, but not to any purpose, rather simply because the author shrinks from nothing in his desperation to be “readable and entertaining”.

But what is in between is both entertaining and informing. It is much more about Langlands, one of the great modern mathematicians than about the book he is reviewing.