Kindle for iPhone is mostly self-explanatory. This is not a standalone app but requires you to have a Kindle account at Amazon. Then, those titles you buy and add to your Kindle account are synchronised with the iPhone. As for the app itself, features include bookmarking (+/-), Go to page, font size and colour, and manual syncing. You can’t fault Amazon for whether you enjoy reading on an iPhone; a Kindle for iPad app would likely be a better experience.