At first blush, Amazon's new Kindle Unlimited book service sounds like a great deal. For $10 a month, U.S. residents get unlimited access to 600,000 ebooks (and 2,000-plus audiobooks), all readable using Amazon's Kindle app. In addition to Amazon's own devices, the Kindle app works on iPhones, iPads, Android devices, and Windows Phones.
Contrast that with Oyster's U.S.-only unlimited e-book service, which also costs $10/month and runs on both on Android and iOS platforms. Oyster has access to 500,000-plus ebooks, while another Kindle Unlimited rival, Scribd, offers 400,000 titles in its unlimited e-book library. Of course, at $9 per month, Scribd is also less expensive and is available in more than 100 countries; its apps run on Android, iOS, and Kindle Fire, plus there's a web interface for PC reading.
But there's more to raw numbers when comparing Kindle Unlimited to competing services--you also need to look at what makes up those 600,000 titles. And the Kindle Unlimited library doesn't include anything from the publishing industry's Big Five: Hachette, HarperCollins, MacMillan, Penguin, and Simon & Schuster. These publishers haven't signed deals with Amazon, as they spar with the retail giant over pricing. (And considering Amazon's ongoing standoff with Hachette, don't expect a resolution any time soon.)
In contrast, Oyster and Scribed can both boast of deals with HarperCollins and Simon & Schuster, which help to fill out their libraries with ebooks from Stephen King, Ernest Hemingway, Mary Higgins Clark, Ray Bradbury, Walter Isaacson, Dan Brown, Janet Evanovich, Neil Gaiman, and more. They don't have deals with Hachette, Macmillan, or Penguin Random House, though.
But even without the Big Five on board, Kindle Unlimited does have major titles such as the Harry Potter series and The Hunger Games books. Still, there's no doubt that the more major publishers an ebook service can draw from, the better the selection it can offer. This is why unlimited ebook fans would be wise to test all three services--Oyster and Scribd each offer a free month for newbies and Kindle Unlimited is launching with its own 30-day trial--to see whose mix of unlimited ebooks suits them best.