Looking at examples using XScope color blind modes, the default colors, and a few different colors (such as reds and greens), iOS7 is far more legible in color

Looking at examples using XScope color blind modes, the default colors, and a few different colors (such as reds and greens), iOS7 is far more legible in color blind reduced palettes than iOS6 is that I can see. If you turn on the "thicken text" (not the actual name) in accesability, they stand out even more.