Not bad, however I see a couple of things wrong with it.
The way you erased the "strands," if you will, of color is a bit too repetitive and looks un-natural. Say, you erased one side of a particular strand, but not the other. Not to mention its too easy to tell they same brush was used to erase them, especially on the left-most red one. You also failed to erase the right-most strands, and while were there, it looks as if you deserted that side of the sig. Put some more work into the right side of the sig, its a must.
Some parts of the sig also look a bit too sharp. Try either sharpening/defining the stock, or blurring the rest of the sig a bit. Especially the noise-like effect youve got on there.
Other than that, its pretty good. I would love to this being worked in a maybe full-sized piece, perhaps a wallpaper? Think 'bout it