This slim volume (119 pages minus lists, acknowledgments, index, etc.) seems intended more for an academic environment rather than a general reader (which is not a criticism, simply an observation).
The book consists of the following sections: An introduction "Why Translation Matters," followed by three chapters: "Authors, Translators, and Readers Today," "Translating Cervantes" (Grossman is quite well-known for her exceptional new translation of Don Quixote (~2002, I believe), and "Translating Poetry." Additional material includes a short "Personal List of Important Translations."
As others have noted, Grossman exclusively discusses literary translation, so the book may more accurately have been entitled "Why Literary Translation Matters."
I completely agree with the author's premise and believe she effectively builds her case as to the huge cultural importance of literary translation, without which, obviously we would only have access to literature originally written in languages we can personally read, which would limit most Americans' options to just English, or possibly one additional language in a few instances.
(Practically) no American living would be able to read Dante, Dostoevsky, Nietzsche, Ovid, Homer, Sartre, and Cervantes all in their original languages, so the cultural necessity of translation seems self-evident.
Perhaps less self-evident is the additional fact that translation has enriched our vocabulary. To illustrate, the author provides a list of lexical items etymologically rooted in Gaelic, for example.
I also agree with the author's premise that the reading public and literary reviewers often take for granted the skill and artistry required of translators to recreate a piece of literature in a new language. She elaborates this point throughout the book with numerous anecdotes, quotes, and observations.
The book is certainly well-written and boasts an amazing vocabulary: even the most literate reader will surely be sent scurrying to the dictionary a number of times before finishing the book.
Additionally, the author includes a number of insightful quotes from writers and translators throughout history, including a quote from the translators of the King James Bible in 1611:
"Translation it is that openeth the window, to let in the light; that breaketh the shell, that we may eat the kernel; that putteth aside the curtain, that we may look into the most holy place; that removeth the cover of the well, that we may come by the water."
I also completely agree with the author's philosophy of translation. At one point, she states: "... a translator's fidelity is not to lexical pairings but to context—the implications and echoes of the first author's tone, intention, and level of discourse."
As other reviewers have noted, there is some repetition (particularly regarding the observation of how reviewers mostly ignore or discount translations) throughout the short book, perhaps owing to the book's origin as separate talks given (as explained in the author's preface).
At any rate, some good, accurate, informative bits, well written. Translators would find much of interest, but I wouldn't especially recommend this book for the general reader, however, due to its format and style.