Illustration - "It's Not Easy Being Green"

Thomas Gomes "It's Not Easy Being Green" 2013

I've been watching a lot of movies and games recently that revolve around zombies or infected.  I couldn't help but do a small illustration of zombies!  As with most of my drawings it started off as a sketch which I then developed into a final drawing. 

The tag line "It's Not Easy Being Green" was added in later, after I had finished the initial drawing.  As usual I am sticking to a certain style of illustration which I'm finding more and more uses for.  I'm interested in any comments that people have on this illustration and particularly the style of illustration that I'm employing here.