The app just lets you read the books you would have purchased for your Kindle. Just keep in mind the best thing about the Kindle is being able to read it in any light and that it does not strain your eyes.
Ever since I got my Kindle, I read every night before I go to back. I used to never read and used to ahte it too. But all of these light novels are great. I've read Toradora, Familiar of Zero (which needs more volumes translated!!) and am working on Chrome Shelled Regios (I think I liked the anime better, haha).