There is 3 things missing in an otherwise good camera app.
Exposure compensation is far to rough. Make it in steps of 1/3 step from -2 to +2.
In Pro mode there must be a custom white balance mode. Plz look at Samsung's wb solution, a slide in Kelvin degrees.
One more thing missing is an exposure and focus lock.
ADD those three things and the camera app is worthy the Pro mode. Development plz look into this!