For those with bad eyes, is the new OS easier to read, harder, or about the same?
The place where I've seen MAJOR improvement in this area with iOS7 has been when running iPhone apps on an iPad (in my case, an iPad 2 -- the oldest iPad supported by iOS7).
In iOS6 and prior, when running an iPhone app you had a choice between running it at its native resolution (and it would always choose the older 480x320 used by all iPhones up to (but not including) the iPhone 4) as a tiny window in the centre of the screen, or running it at "2x", doing a straight pixel doubling of everything. Fonts in particular became pretty ugly scaled this way -- they became obviously pixellated.
In iOS7 however, all iPhone apps are auto-scaled. It appears it now prefers graphics for the iPhone 4/4s screen resolution (940x640). Most importantly,
the fonts are simply sized to the correct 2x size without pixel doubling -- so the render to the correct size at native resolution. This makes iPhone apps on the iPad vastly easier to read.
I can be a bit jarring mind you when you couple the new, crisp text with a graphic containing text designed for the pre- iPhone 4 screen resolution. The graphic gets scaled, so any graphical text looks pixellated still, however UI fonts in the same display will be crisp and clean.
I don't run a lot of iPhone apps on my iPad -- most are either dual iPhone/iPad apps in the first place, or have iPad equivalents available in the app store. There are a few that I need to run however (my banking and insurance apps don't have iPad equivalents, for example), and the text quality improvement in them is tremendous. It was pretty much worth the iOS7 upgrade alone for those apps.
None of which is helpful on an iPhone of course, and not having an iPhone (or bad eyes for that matter) I can't comment on how easy to read the text is on those devices. They certain do appear to have taken some time to improve things on the iPad however, and there I've ben really happy with the new and improved font rendering support.