Due to the greater popularity of Neal Stephenson's previous novel Snow Crash, I'd imagine that most people considering reading The Diamond Age, like myself, enjoyed reading the former and then proceeded to wonder how his later work compared.
The Diamond Age is set many decades after Snow Crash, but you'd scarcely realise it's the same fictional world due to the stark contrast of the style and setting between the two novels.
The countless competing cultures, franchise-organised quasi-national entities and corporations which populated Snow Crash have, by the time of The Diamond Age, mostly boiled down to high tech facsimiles of Victorian England and ancient China, nicely paving the way to the author's later historical work, Cryptonomicon and The Baroque Cycle.
Appropriately enough, The Diamond Age is primarily about a lower class girl, Nell, who stumbles across an interactive book which teaches her how to grow up to become a true queen. In fitting with such a Victorian plot, the prose is rich and even the chapter titles are detailed. This is just as much an imitation of Victorian sensibilities and style as Snow Crash is a representation of cold, franchised ruthlessness. It's no surprise that the latter found a larger contemporary audience.
Another sensibility employed by the author which seems to have been plucked from the Victorian and ancient Chinese cultures is the emphasis on the importance of subtle nuances of etiquette, something you don't often read about in speculative fiction written for hackers. Whether this is to the novel's benefit or detriment is, of course, dependent on the individual reader's taste.
This isn't a book you should read for immediate thrilling entertainment so much as subtle contemplation. You may feel like its pace is slow and not much gets around to happening, and yet months after finishing it you might find yourself fondly recalling the odd snatch of dialogue here or the wry observation there, only to give in and read it all over again. This book is filled with the kind of phrases you'd want to quote to your friends, only they would scarcely make sense out of context.
This is the first of Stephenson's books which I didn't particularly enjoy reading the first time around, in as much as the narrative, as charming and detailed as it is, is such at the expense of being gripping or having much immediate action. You may ask, if I didn't enjoy reading it, why I continued to read his other works and even re-read this one. I read this, and will continue to read Stephenson's other post-Snow-Crash novels, because they fill my mind with interesting ideas and set me wandering down various different paths of thought, further exploring the ideas he presents. These books are the vegetables of the novel world. You won't necessarily immediately enjoy them, but you'll nevertheless benefit from consuming them, something you may perhaps only appreciate a while after the fact.
One of the ideas Stephenson meditates on is about how being raised by an interactive book would affect a child's psyche, and who she would then grow up to be. As one might expect from a novelist who would go on to write with fountain pens on cotton paper and typeset in TeX using Emacs, The Diamond Age is practically a love letter to the medium of the book, that stresses the importance of virtues such as literacy in an imagined future that no longer requires it of its citizens.
You must enjoy reading novels for the sake of it if you're to have any hope of reading anything written by Neal Stephenson since Snow Crash. Stephenson's the kind of person who, if he were to show a character drinking a cup of coffee, would spend several pages detailing the history of coffee houses and showing farmers toiling in their fields before doing so. Unlike Snow Crash, whose hyperbolic, stylised prose betrays its comic book roots, his later work is written as florid prose for old fashioned hardcover book fanatics.
Usually novels are entertainment, read for the primary purpose of exciting the reader, invoking various emotions so she can vicariously live the life of the protagonist. While I'm not entirely convinced that The Diamond Age is gripping as a work of fiction, it's certainly fulfilling the additional roles of a good piece of science fiction, namely to make you think about how it would play out if someone made a particular invention.
In this case, the invention happens to be an interactive book that can almost singlehandedly raise children. An even more important invention, a matter compiler that can create objects out of practically thin air, is already well established by the time of the story's setting, while another, that decentralises the former to completely get rid of authority, is on the verge of being realised. In spite of the enormous impact such inventions would obviously have on societies, the accompanying political struggles seem somewhat forced into the background, allowing Stephenson to concentrate most of his efforts on one main idea of an interactive child-rearing book.
A few themes seem to have become Stephenson staples: there's another example of propagating information via sexual intercourse, this time resplendent with accessories that glow in the dark as part of a strange ritual, but thankfully it's not dwelled upon too much, although it frankly seems somewhat out of place amongst the relatively highbrow main topics; Stephenson continues to use ravens and coyotes as villains, something one of his characters later explains in Cryptonomicon; and there's a reasonable amount of learning about Turing machines. However, all these themes are squarely secondary in comparison to the interactive book.
If these ideas intrigue you, or indeed if ideas in general appeal to you just as much as action, you may just get something out of this weighty tome. In that sense, it's science fiction for responsible adults.