I think what you've got here is a design that really should have been refined a little more before you went into the details phase.  In general, your shading, texture, etc are pretty solid, but there are some issues with the basic linework that are keeping it from being as good as it should be.
I think the first thing is general proportions.  On the one hand, yes, this is a cyborgyetiman, so accuracy to life isn't perhaps a top priority.  But at the same time, things like his lack of forehead, different leg lengths, uncomfortable-looking right arm (our left) can detract from the piece.
Another thing to consider is the silhouette/general composition.  The silhouette of a piece says a lot about how you'll view it--if it's recognizable and has a good "flow" to it, the entire piece can be enchanced.  As it stands, I think his pose is a little "flyswatted", as Arne puts it (in his fantastic tutorial).  There isn't really a flow to it.  You've also put his chest and shoulders in near-profile, but his hips and head in a more 3/4 view.  That's tempting because you want to show off all of his cool accessories, but it's pretty much always better to have a good composition--everything looks cooler that way.
Here's a quick silhouedit, with yours on the left, and a potential revision on the right.  It's certainly not the only possibility, but it's not that far from what you have already, and it's a relatively popular choice, basically a standard contrapposto (popular with artists as diverse as Donatello and Adarias).  The < leg is engaged and bearing most of the weight, leaving the > leg ready for movement, and lending the entire body a bit of a pleasing s-curve.  It's rough, but the basics are there.

Anyway, I think you've got a good thing going here, but you could get a lot more out of it with a little more effort.

Thanks for posting these!  I'll certainly be using them for reference, especially the snowy trees--I'm quite impressed by how you managed to get the snowiness with just(?) a palette swap.  I'm not quite sure what's going on with the bushes, though (I think they're bushes?  the ones with the red flowers/fruit).  The shaping seems a little odd, and the lighting is kind of uniform, so I don't get the same sense of depth that I do from the trees.

Since the project is dead, have you considered releasing them under an open license (eg one of the Creative Commons licenses)?  I can understand that there can be (plenty of) reasons to not want to, but someone might really appreciate being able to use them.

I don't dislike the skin at all, but I don't like changing something that I like and am used to.  For that reason I would appreciate an option to change back to the original skin, were that an easy thing to do.

He reminds me very much of Lex Luthor, especially the Animated Series version.  And not just because he's bald!  The expression seems to carry a certain degree of both confidence and contempt, as if to say that he is so thoroughly sure of his own worth that he doesn't think twice about questioning yours, and is sure that you are wasting his time.  Sort of like this, though of course more effective.