From Slate, “The Ghost in the Machine” (December 3, 2012):
“…At the moment, e-book sales account for more than 20 percent of dollars that consumers spend on books. Almost all of that market share belongs to the “print mimic”-style e-books. But there’s also an emerging category called enhanced e-books—digital editions with special features like audio and video—that are more than just mimics. Or at least they can be, in the right hands.
…Enhanced e-books are rare in publishing because they’re expensive to produce, and the audience is, for the moment, pretty limited. (Some enhanced e-books, including The Fifty Year Sword, can be viewed only on an iPad.) “We’re finding that the effort behind these types of books is a magnitude of somewhere between seven and 15 times as much effort as a typical illustrated e-book,” said Liisa McCloy-Kelley, head of the digital production group at Random House (which owns Pantheon). To complicate matters, the differences among rapidly evolving platforms and formats make enhanced e-books difficult to market, even to tech-savvy consumers.”