Being a fan of Killer Klowns and all that, I like the look - I just don't think I'd add too many "veins" (and, of course, I don't know how many you were planning to add).
What I'm trying to get at here is it looks pretty good - I don't know if I'd tweak it too much for concern of the tweaks overtaking the power of the face itself.
My two cents (and trust me, I know nothing about mask building).