Reminds me of Da Vinci's "vitruvian man" with that circle background and the pose.
Great work on the metal, since not only can you tell it's metal you've given the flat areas enough texture and detail so that it does't look boring.
Anatomy's spot on but then again you seem to be pretty experienced with that anyway. Now for some legs! I'm thinking he can fly, add a dystopic future battlefield with some interesting effects and backlighting and you'll have yourself a frontpaged piece of art easily.