I like your style, place a light blue or red black swirl in that sholder ring. Slim his waist line to give his chest more of a "big" apperence. I would lose the one big spike on his arm and give him small ones at the wrist and larger ones as it goes up the arm, if he were to lift his arm his big spike would hit the sholder spikes...I like the sholder spikes. One last thing if I may, the dim arm that isn't noticable, make it some kind of mech arm, nothing fancy due to the rags, but somthing practicle, not pretty or nice to look at.
Hope you like my critiques, I lllloove art, pm me and I'll add you and we can show each other our works. ^^