First to the weaknesses of Robin Sloan's first novel, all of which are ironic:
For a book about books, there's little sense of what it's like to read a book, and little reading of actual books. Most of the books here, all hardbound tomes, are texts to decipher rather than stories to read. The contents seem to be irrelevant (I may have missed something here) except insofar as they lead to the next book in a cycle. The one book that, as a story, is important (though you know all along that it will factor into the endgame) only becomes crucial when listened to—and although I know the importance of reading aloud, the experience of listening to a book on tape seems mispraised, and the book being listened to isn't well written enough to even be interesting when read aloud.
Additionally, the writing in this novel is . . . brisk. It does what it needs to do, but there's not a single sentence over which one might linger. The writing is clear, but not worth attention as writing.
Finally, the argument in favor of books and bookstores seems built on their accidents rather than their essence (if I may be so Aristotelian). All of us who love books do, in part, love their appeal to the senses, and all of us who love bookstores have attachments both sensual and nostalgic to the experience of bookstores and the books we purchased there. However, that's not quite the same as arguing in favor of books as books or for the continued existence of bookstores (and Mr. Penumbra's is, for much of the book, ill-supplied with good reading material).
Moving on to what I liked . . .
What the book does well is manifold. Though the writing isn't special—and relies on the kind of clichés of suspense you've seen many times before—Sloan does a great job incorporating the latest language of social and online discourse in a way that sounds natural. This, I think, is a major achievement. One reason Stephen King's narrative voice grates so on me is his self-conscious dropping of brand names and working-class codewords; it's an insistent style that's never felt smooth. Sloan manages to pull off something similar, a style that slides high (though not very high) to low smoothly, sounding contemporary without sounding forced.
Sloan clearly loves both the world of Google and the world of "OK," Old Knowledge, the "facts" that will die if we don't save all the books but also the facts that inevitably die with the passing of any one person. People throughout the novel display incredible skill in searching through the power of Google and the massed computing of many countries, but the human element often trumps this great mechanistic might.
Sloan moves between the real world (the Google campus) and invented facts about the world (a fictional ubiquitous font) with slick cleverness. Characters matter-of-factly describe real-world details that aren't at all true, pulling us into the narrative Sloan wants to tell without letting slip how much of it is fantasy. Well played.
The story itself is something of a poor man's Umberto Eco, a bit of Name of the Rose and Foucault's Pendulum, but without the density or breadth or on-display literateness. Like both of those books, part of the point is that the solution to huge mysteries is usually less interesting than the search, and that these mysteries we create often miss the greatest mystery, which is ourselves, our own fragile life here. Sloan fashions a quest narrative that raises questions about the value of human endeavor, and it's not a question he raises only to dismiss it. It is, in fact, the true conflict of the novel, as every character is engaged, in one way or another, with making a mark on the world, establishing a name, aiming to endure. These are ideas worth reflecting on, and Sloan studies them from several angles in order to arrive at his conclusion.
And now I must address further my disappointments. The puzzle of the book is fine, and Sloan takes us to fun places to explore that puzzle, but aspects of the solution feel like a cheat, and I'm unconvinced by the final solution, which seems not only muddy but, if I understood correctly, not likely to have been achieved in the century it was set in steel. Also, and more problematic, the protagonist gives a slide show at the end of the novel . . . and only one of the slides is described, and that one as a sort of by-the-way. It's as if Sloan thought his publisher would be putting in some color plates for us to view, but those never made it to the printer. It's one more puzzle in a book filled with them.
In conclusion: I enjoyed it, it reads fast, and the author does some fine work, but in retrospect the book feels thin and not the best way to have spent my time.