The Kindle eReader runs on a customized version of the Linux operating system, as does its tablet counterpart, the Kindle Fire, which runs on a modified version of Android. Stripped down, it's designed to have few functions other than displaying eBooks and connecting to the Amazon Store with the user's profile (and social media), although other functions exist, such as rudimentary web browser that's buried in its settings. While its software functionality is fairly limited, the advantage of its operating system being based on Linux is that it opens the Kindle to the possibility of customization.
Since Linux is Open Source, it's unsurprising that there's an active community of modders that has listed detailed instructions on how to "jailbreak" your Kindle, enabling the user to make changes that would otherwise be disallowed. For example, a user might want to customize the Kindle's screensaver so that it displays the cover of the book she's currently reading instead its carousel of stock images, or use their Kindle as an external monitor for users who suffer from Computer Vision Syndrome. The downside is that jailbreaking is a rather involved process; users who aren't particularly comfortable with the inherent risks are facing a pretty steep barrier. Ideally, some of these options should be more easily accessed.
The Amazon Store on the Kindle has evolved quite a bit since it first debuted, from a digital storefront to becoming more of a social reading space. The store now boasts a mixture of purchasing and "borrowing" functions, including individual, one-click buys, an "owner's lending library" affording a user to borrow one book per month (restricted to members of Amazon Prime), and a subscription-based "unlimited" model for buffet-style access. In addition, the Kindle storefront acts as a portal to Goodreads, a social networking site for bibliophiles (also owned by Amazon). It's evident that Amazon recognizes how social reading can encourage book sales, and the "lending library" mimes the community library--all acknowledgements of the power of community in cultural exchange.
Moreover, Amazon has taken steps to allow users to "share" books with family members and friends, within limits, and only if all members are registered with Amazon. That said, not all members need to own a Kindle; one can read borrowed books through the Kindle App on a smart phone or other device.
What about material from outside Amazon's store? A user can add books or documents by sending files directly through email or an app to a Kindle. However, those files must conform to a select group (including plain text, Rich Text, HTML, MS Word, PDF, and image files); what is conspicuously absent are other eReader formats, such as EPUB.
The strongest argument against the Kindle is Amazon's file format policy. In contrast to the open EPUB file format, Amazon prefers to use its DRM (Digital Rights Management) schema for its native AZW file format (a wrapped MOBI file). As a business model, this makes a certain amount of sense; it's standard practice to protect media content from easy replication and redistribution. However, even if a user has bought and paid for an eBook (which isn't actually the case), any manipulation of that file is jealously guarded--if a user wants to pull a file from a Kindle for research purposes, the user has to follow a labyrinthine maze of steps simply to access the file--it's not as simple as plugging in the Kindle to a USB port and copying a file onto a laptop. There are, of course, software solutions that can circumvent these restrictions, but as with jailbreaking, these are more steps than the typical reader is willing to take. There's no technical reason why the Kindle shouldn't be able to read EPUB e-books, or for curious users to be able to manipulate their e-books; but Amazon's strict restrictions creates enough burdens to discourage the majority of users.
In one sense, much is owed to the Amazon Kindle for popularizing eReaders. It certainly wasn't the first eReader (that honor goes to the Sony Librie, way back in 2004) to be available for mass consumption, but it was the first to be subsidized by Amazon's vast resources, making eReaders affordable enough for many people. The Kindle continues to evolve and improve yearly, with better specs, more storage, improved software, and slightly more, if begrudging, gestures to book sharing capabilities.
Still, I can't help but liken the Kindle to a Trojan Horse. By lowering the price enough that the Kindle penetrated a wide swath of households, combined with its proprietary file format and strongarm tactics with publishers guaranteed a stranglehold on the mass eReading public. With many of its competitors sidelined, the Kindle is quickly reaching the point of a complete dominance over the eReader market.
That alone should be enough to give the thoughtful reader, and certainly the critic, pause. Amazon's priority in broadening access to its store and books are not necessarily in service to the reading public, but its shareholders--and that informs every design and policy decision, from top to bottom. I think a better balance between quarterly earnings and greater access to knowledge and culture should and can be struck. Personally, I'm looking for a more open alternative.
Darnton, Robert. The Case for Books: Past, Present, and Future. New York: PublicAffairs, 2010.
Roh, David S. "Unwrapping the eReader: On the Politics of Electronic Reading Platforms” in The Bloomsbury Handbook of Electronic Literature, Tabbi, Joseph, ed. New York: Bloomsbury Academic (2017): 371-384.
Sellen, Abigail J., and Richard H. R. Harper. The Myth of the Paperless Office. The MIT Press, 2003.