It doesn't launch as another app in your dock, instead it sits in your (albeit overcrowded) menu bar, and provides only a few sparse settings - the background color to use, whether to make the backdrop opaque (so you can see the desktop underneath it), whether it should start when you log in or activate automatically, and what key shortcut should activate/deactivate it.

...Having only used it for a short while I can't proclaim how it has saved me x hours per week or saved the lives of thirty-three cats, but even after my limited use it looks to be an app well worth using.