If you mean the quality of the pictures at any given camera setting, that's very unlikely.
The phone (including the camera) may become slower & less responsive over time, but shutting it down (to clear the memory) then restarting it should restore some performance when that happens.
Also, keep a healthy amount of free space in the camera's storage 'cos filling it up with a gazillion apps will also slow it down.
But the picture quality of the camera itself should remain fairly constant at any given camera setting.
If you're genuinely concerned about picture quality you should be using a "real camera" to be honest, unless you've got an iPhone or iPad -- pains me to admit it but their built-in camera can match my SLR gear for quality...