Feels like there should be some text or something off to the left side. Otherwise, it all looks great to me.
It's the Big Sister from Bioshock 2. I think it looks pretty nice, as others have said I think the left side needs something but I don't quite know what. Maybe a C4D of some sort or something?
Maybe try a nice bold font, then modify it a bit on your own (grunge it up, maybe), and place it so it's not entirely on the sig. That's what I'd do at least.
I was going to work on the texture and definition of that rock on the left, that's the problem. And @ Sam, I wanted to do a tag without any external effects, just the stock.