It works really well and the 'reading experience' is very good. Once you've downloaded and installed the app and logged in to your Amazon account, it 'knows' that you have an iPad and any book purchases are automatically downloaded to your iPad.
When you install the Kindle app it comes with a few free books, which means that you can try it out and see if you like the 'experience' before actually purchasing any more books. There are also quite a few 'free' books available on the Amazon site - mainly classic novels.
Tim
Scotland