Im curious on how youre going to model this, i suspect youre going to load this low poly model with some sort of mesh smooth on it into a program like mudbox or zbrush, so that you can detail it a little better, making muscles using box modeling is a pain if youre going for realism, also how big will he be in game cause that should influence how much detail you add to it, sometimes adding too much detail blurs the subject and makes it look too busy
i plan on making it into a legitimate game model that a 3D game could use. he'll be small in my 2D construct game, so hyper detail isn't important. the art style is also going to be pretty abstract in the 2D game. but i'm keeping tri numbers of the model low enough so i can use it for a 3D game if i wanted.
it's flat shaded in those pictures, but with the same polygons rendered in smooth shading, it won't have this blocky look to it.
edit: here's a pic to show flat and smooth shading with the same exact model (with a deadpool texture projected onto the side):
<img src="http://upload.dfyb.net/uploaded/shading_properties.png">