I don't really like it :| I like it more when it's less.. Hard. Like, without the hard lines and sides.
My biggest "problem" (for lack of a better term) with this signature is the Blue comming off Shadow's fist. To me, the blue clashes with the background color and off-sets the entire signature. I also find the font to be a little... odd. Not sure why though. It just doesn't agree with my eyes; which could be a biased opinion since I tend to prefer more feminine fonts (example: Punkydew's signature). Still, this is much better then what I am capable of. Me three.
id say try to incorporate the colors of the render into the background with a smudge tool, the background on there now is great imo but the blue really stood out to me, great work though