The goal was to carry the spirit of Mr. Reader to the new OS. So the icon needed to feel lighter and right at home on iOS 7. I won’t lie, the design process itself for a typical icon of the new platform which iOS 7 is, allows for a much more simpler approach than in the pre-iOS 7 era. With iOS 7 icons you spend more time thinking about what works best with Apple’s paradigm of minimalism, rather than fine-tuning every pixel of a drop-shadow.
Nice overview of the design process behind the new Mr. Reader icon.