If you're not a fan of the iBooks app, or have already invested in another ecosystem, don't panic. Within the App Store, there are over 55,000 apps listed under the Books category, including full support for competing services, like Kindle, Nook and other popular (and not so popular) e-book readers. If you like comic books, there are plenty of choices here, too, with Marvel, DC and Image -- among others -- offering comics for purchase and download to their respective apps.
Apple also spotlights your newspaper and magazine subscriptions in the form of Newsstand, a specialized home screen folder that, when tapped, offers access to all of your subscriptions. There is an option to automatically download content when a change is detected, assuring that whenever you check the Newsstand, the information you are accessing is up to date. The Newsstand icon displays a numbered badge when updates are released. (The icons for newspapers and magazines -- which sit on virtual shelves in Newsstand -- also update themselves to represent the latest cover, which is a nice touch.)
On the other hand, Apple is having some trouble with the government for alleged antitrust actions having to do with e-books: A year ago, the U.S. Justice Department charged that Apple spearheaded a scheme with book publishers to keep the prices of e-books artificially high; on July 10, Apple was found guilty of violating antitrust laws. As of this writing, it was not clear whether the outcome would affect the pricing of Apple's e-books or, ultimately, its market share in the long term.
The Google Play Store has robust sections devoted to book- and magazine-based content. Following the cross-platform model, titles purchased from the Play Store are automatically synced across all devices and can be read on any Android phone or tablet as well as on any other Web-connected device.
Google also has a separate service named -- somewhat confusingly -- Google Books. That service allows you to search for content within actual books and magazines and to read excerpts or full text of some titles. Google Books has been the subject of much controversy within the publishing world because of the complex rights issues related to Google's scanning of older print editions.
If you're looking to buy magazines and books, Microsoft's isn't the ecosystem to go to. This is especially surprising, given that the company invested $300 million in the Nook business, which is built on book and magazine purchasing.
That being said, there is a Microsoft place to go to buy books and magazines: the Windows Store on Windows 8 or on a Windows Phone device. There you'll find a relatively small selection of books and book-related apps, and newspapers and magazines and related apps. So you can buy Dr. Seuss books for your kids, for example, or a variety of dictionaries. But there are very few offerings -- the entire Books & Reference section in the Windows Store, when I last checked, was 1,666 apps and books. For magazines, check the News & Weather section. Again, though, the pickings are slim -- 1,019 apps, and the vast majority of them area news-related apps rather than actual magazines.