its cool, but i dislike how light the picture is

id prefer if u darkened the whole thing, but taht is a preference

The sig is kind of boring.
Centered focal is a problem. http://en.wikipedia.org/wiki/Rule_of_thirds
The link is to the rule of thirds. If you follow it, the sig will become more appealing to the eye.

Make sure you are using a high quality stock/render. The one you are using doesn't look too bad.
However the lightning flash isn't very high quality.
I also don't get the greyness

The text looks really ugly scrap it.

You used a render with a lot of flow, but you aren't utilizing the flow at all.

for example:

Look at how the effects flow with the render.

You need to read some good tut's

Here is a good starting one:
http://senthrax.deviantart.com/art/Full-Signature-Tutorial-55042010

There's a huges lack of depth here. The text is horrible .. It looks like a stock from ms paint or something lol.. The effects/placemanet are also a problem. You should definitely look into some good tuts as a guideline. I don't think you should duplicate your render like that in the back looks odd =\ also verryy bright O_O . Have you tried using c4ds/brushes/smudging? Those will also help you increase depth/flow.