There is a good Kindle app and several other ebook readers available for the iPhone. Since the Kindle uses the AT&T network you will have the same download capability (better in 3G areas actually). If you put the iPhone in "airplane mode" where it's not using the radios then battery life is quite good. Battery life is not as good as the Kindle but the Kindle won't act as a GPS, camera, web browser, etc. Plus the iPhone weighs a lot less too.