I only recently (2 days ago) became true owner of a Kindle, so I have been reading books on my iPhone 4. I thought the display was pretty good, but after loading this update I didn't know what I was missing. The iPhone screen is a bit small for reading books, so every possible pixel is useful and it shows. The sharpness seems much greater, which I find the most important quality. A nice update, although you have to wonder why it took them this long to release it.
The update also includes some nice changes in how book are organized, downloaded and displayed. Nice touches, all.
Apple launches iTunes section for Retina Display-ready
iPad apps from AppleInsider
In preparation of the upcoming Friday launch of its new iPad, Apple on Thursday put together a list of 24 apps that best utilize the new tablet's high resolution Retina Display.