Really?
I didn't ask for "parallax" backgrounds.
Well, at least this is one thing you can turn off.
Settings > General > Accessibility > Reduce Motion > Set to ON
The description says it "reduces" the effect, but I have pretty sharp eyes when it comes to this kind of thing, and after turning reduce motion on I can't discern a parallax effect at all anymore.
Of course, I'm sure that won't be enough to sell you on ios 7, but it can be beneficial information for others reading this thread that don't know parallax can be turned off.