I own both a Kindle and an iPad and have used both for reading books. I prefer reading on the Kindle because of the eInk screen, weight of the device and the orientation of the buttons. I do find the iPad has a much more engaging screen and is a very usable reader, except when it comes to reading outside. I made the mistake of taking my iPad with me to the park to read; the glare was far too much, even in the shade.

Ultimately for me it feels better to read on the Kindle. The Kindle is made for reading and it shows in the engineering, just as the iPad is a multimedia device that has a few apps for reading books.