Good work on the skin texture. Looks all shiny and reflective (which may in fact be one and the same thing in this context, now that I think about it), but not ridiculously overly so.
It *could* have perhaps used some smoothing, so that the individual strokes aren't this visible, but I suppose this may just be your preference, so nevermind.
Nice similarity at any rate, especially on the... actually, nice similarity overall - I've hardly seen a lot of that series, yet I recognized him from the gallery thumbnail instantly (and I do mean instantly, as in, even before the synapses associated the name and the gold forehead thing to a face). Eyes, no, eyebrows look a bit... I don't know, feminine perhaps? Other than that, it's very good though.
I was mostly testing out the oil paint brushes. I like trying them all out on a sketch and saving the ones I like in a new custom palette. It takes awhile but it is the best way to find brushes that suit your painting needs.