So I have more adventure in getting iOS 7 on my iPhone 4S: I found that when I would unlock my phone or browse the home screen the user interface would have some lag and be slow to respond.
I think it’s because of the new wallpaper settings that move when you tilt the phone… (and it changed my wallpapers that didn’t fit my screen’s resolution like it did in iOS 6.
So to turn off the moving “parallax” effect, go to the Settings app, go to General –> Accessibility –> Reduce Motion and turn the setting on.