This is a collection of 17 short essays about J.R.R. Tolkien penned by contemporary fantasy & sci-fi authors. (Actually, 15 essays are by authors-- one is by bibliographer/editor Douglas Andersson and another is an interview with the Hildebrant Brothers, who are reknowned fantasy artists).
As others have noted, the essays are something of a mixed bag. Of them, only three try to take a critical, scholarly, analytical look at Tolkien. This is probably for the best, as authors usually make terrible critics. Of these three, the strongest is Ursula LeGuin's discussion of the poetic rhythms in Tolkien's prose. While thoughtful, it is nonetheless a bit dull-- and frankly, a much better essay on this same subject can be found in _J.R.R. Tolkien and his Literary Resonances_. The weakest of these three, Orson Scott Card's essay on "How Tolkien Means", is also the worst in the whole book. Although his basic contention-- that the essence of Tolkien's fiction lies in "Story" rather than "Meaning"-- is reasonable enough, his point is overwhelmed by an arrogant tone and intermittent rantings against feminists, multiculturalists, literary critics, People for the Ethical Treatment of Animals, Sigmund Freud, James Joyce, people who like James Joyce, modernists, postmodernists, and pretty much anyone and everyone who doesn't share (or whom he suspects might not share) the exact same approach to literature as he does.
Most authors here, however, have (wisely) avoided criticism, analysis, and polemic-- and have instead penned more autobiographical essays, reflecting upon how/when/why they first read Tolkien, how it impacted them both immediately and later on, how it changed their reading habits, how it influenced their own writing, and the like. Although these essays all have their own unique character and specific content depending on each author's own experiences and style (unsurprisingly, the essays by Terry Pratchett and Esther Freisner are quite funny), one can't help but note a common pattern of experience. With one or two exceptions, most of the writers here encountered Tolkien for the first time as an adolescent during the 1960s. Most describe reading the _Hobbit_ and the _Lord of the Rings_ as a life-changing event-- as a kind of epiphany or even as a magical experience. Many say that reading Tolkien inspired them to become writers themselves-- and several describe how many of their own early works were specifically modeled on Tolkien. Virtually all observe note that they probably could never have made a living writing the kind of fantasy fiction that they do if Tolkien hadn't proven to publishers that there was a huge market for this sort of thing.
Of all the essays in the book, the hands-down best is Michael Swanwick's "A Changeling Returns", an introspective piece that contrasts his childhood memories of reading Tolkien (where he saw mostly magic, adventure, and freedom), with his adulthood re-readings of it (he now sees that the powerful sense of loss and mortality that permeates Tolkien's fiction), and with the experience of reading Tolkien aloud to his children (who are encountering it as he first did as a child... but who can still sense that there is something deeper, sadder, that lies beneath). Whereas most of the other essays in this book were merely 'interesting', I found this one to be profoundly moving. (Then again, maybe that's just because I found Swanwick's experiences to be closest to my own).
All in all, I can't say that this is a must-have book for either Tolkien fans or scholars, but it does give an intriguing and suggestive first-hand account of how many of today's great fantasy & sci-fi writers have been influenced by Tolkien... although many of the most suggestive elements come not from what individual writers themselves say, but from seeing the commonalities of experience among them. My only real criticism of the book as whole is that it would have been nice to include as a contrast some essays by authors who *aren't* fantasy writers, by authors whose primary language wasn't English, and/or by authors who were of a different generation that those featured here.