I've had to make the font bold and bigger and reduce the brightness to mitigate the "vibration" effect of the horrible default fonts.
My phone now looks like an old persons or kiddie phone with big fonts and bright colours. I no longer feel professional when I take my phone out. I have 20/15 vision and amazing acuity but I have to enable multiple accessiblity low vision options to not get headaches. My email shows half the text it used to on iOS6, I'm processing email half as fast. The big fonts also cause problems with notifications and other popups since some of the text is often hidden.
I see a lot of people saying they like the overall design of iOS7 but basically the awful font choices make this a train wreck for me. Even if a "turn off zooming" option becomes available, I'm still stuck with essentially a half size screen because of the size of the text shown. Increasingly, apps will follow Apple's design lead and one by one my apps will also become unusable unless they follow Apple's accessiblity options (many don't).
Yesterday I found out from my employer that they will pay for a phone. I'm going to get an Android and switch to that as my primary device. I'll keep my iPhone for development and wait and see if they fix iOS7.
What I need is new heavier weighted fonts *and* the zooming turned off.
I'm still dumbfounded at why they picked a thin weighted font and added useless animations. It makes no sense from a design or a usability standpoint. It's almost like this UI was designed for print, like the user interface mockups we used to get from designers in the 90's.