The motion effect on the home and lock screens is one of the new features in iOS 7 which instantly annoyed me. The background appears further away than the icons and text. This is accomplished by moving the background countering the device’s movements. While the effect has some air of novelty to it, it really only conveys depth with one eye closed and your head still. But that’s not my issue with it. The problem is that, if you care even the slightest about framing you can’t use anything other than abstract textures as background. Forget about moving and sizing your background picture, it wont end up in the place or with the size you chose anyway.
Luckily, the motion feature can be turned off. Go to Settings -> General -> Accessibility -> Reduce Motion