The major details are all in, looking fine, oh yeah. It'll be interesting to see how the little creases and textures you add to this bad boy soften the edges to a point where we're looking at a biological entity in "slightly pissed off mode".
As for the neck, I know you've added detail to it, but I would be concerned about it shrinking as-is in the casting process. To make it easier to slip on and off, I would build up the neck a bit more to compensate for that shrinkage. Please tell me you're not going to sculpt the neck ring onto the mask - big no-no. You want it to be separate, so the mask can turn left and right with greater ease.