While the effects themselves aren't that bad, the blending, lighting, and colors are terrible on the eyes.
Play with some adjustments on the stock (Image>Adjustments). Try several gradient maps, with different blending options on different layers of the render. Curves can also do some wonders.
Adjust the saturation of the background, it is too bright and takes away from your focal. Some lighting effects (filter>render>lighting effects, for starters), and blur it, (filter>blur>[try gaussian blur]) to add depth.
The render doesn't stick out enough, and you have way to much empty room on the sig, readjust the size, or fill up the empty space with some c4d effects.
Some text would make it more sig like, and make it less empty, but it has to be done right.
Just some thoughts.