Remind me to get ZBrush... Seriously, this looks brilliant. It is finely detailed and well made. Though, if I have to critique, I'll point out that, to the attentive eye, the symmetry is very clear. You should try to deviate from the symmetry every now and then, just to give it a more realistic look. A great example of this is the creases on his forehead, which are very clear that they have been mirrored. Aside from that, great concept and work!