To be honest, I'm not sure about the text. Maybe you should blend it more with the background and change the position. Also, the "electric" effects you overlayed on the render are too low-detailed, maybe you should replace them by different images of the same effect. About the render, I personally would sharpen it a little bit, and blend more with the background. A color correction also wouldn't be bad. =)
I don't know if it's just me, but I don't "feel" the theme of the sig. Maybe it's due to the background or because of the color scheme you're using. I would change the bg for something that fits better with the render, and try adding some light effects, maybe with different colours.
All in all this is a great sig, there are just some little details that make the difference on the final look of it. Keep going with the good effort mate. =D