I think the sig could use a more interesting backgound behind those brushes, something discreet but more noticable than the brown boring color that is just there.
I also think that it would look better with the guy on top of the brushes instead of beneath. Brushe's color also sticks very much out of the sig and that grey robot just does the fatality to it. The guy at the rigth, however, is O.K. because he has brown hair. You should folow some sort of a color scheme more.
Also you need to redo the font, that one just aint working at all, not only do i not like the pixely style it has, which i usually dont like, then also the color and the placement of it isnt really good, you already have a robot at the left and the character at the rigth, you dont really need the font to be there. I think that the font would look better if it was at the middle of the sig and a more techy looking one. Then also make the color of it have something more to do with the sig.
Overall I'd tell you to redo it. The sig dosent have too much merit because the brushes aint yours, the backgound is boring (behind the brushes), font not good (not to mention badly placed and colored) and the layout aint anything out of this world.
That's about my opinion now =Ã