wow I like it alot... grunge style works out great and the render is nicely blended ( don't know if everyone agrees with me but ok)

but the text(onimaru) doest have the grungy effect as the rest of the sig, maybe you could try to make it blend in more(not that it's blended badly). maybe softly brush over it, make it a little smaller?
add a 1 pix black border and it should be cool...
(note that this is just my opinion, as you are more experienced you might disagree)