When Apple was readying the release of the iPad, there was a debate as to whether or not Apple would actually approve Amazon’s submission of a Kindle application into the App Store. Apple has a history of rejecting applications which duplicate the functionality of Apple’s core applications which are included natively with their iPhone OS class devices. Apple skirted their way around this issue with e-books by making their iBooks application available as a free download rather than as an included application. This way, third-party e-book reader apps can co-exist with iBooks without Apple having to justify why it lets certain types of applications duplicate its core functionality while rejecting others.
Other than iBooks, Kindle is the most prominent e-book reader app available in the App Store. It’s gotten a lot of attention from iPad users, likely because many of them were previously Kindle owners and have a collection of paid-for e-books that they’d like to transfer over to their iPad.
I’ll leave it up to you to decide whether or not you like reading better on an LCD screen or on an E-Ink screen, but I’ve found the overall user experience on the Kindle satisfying. For the most part, iBooks and the kindle app have the same feature set. iBooks does a slightly better job with some of the animations related to opening a book and turning pages, but that’s not a deal breaker.
On a side note, if you have trouble reading for more than twenty or thirty minutes at a time, try switching to white text on a black background. The inverse-color mode produces a lot less light and is much easier on the eyes over a long period of time.
The major difference between iBooks and the Kindle app is the e-book libraries that the two apps have access to. Amazon already has a large line-up of publishers which have entered into agreements to publish books on the Kindle. Publishers don’t necessarily like Kindle because of flat-rate pricing that Amazon demands, nonetheless, the relationships are in place, resulting a very large library of books to choose from. Apple has not done as great of a job in getting publishers lined up and its library isn’t nearly as large as Amazon’s is yet.