I like the character so far, but i seems odd that with all of the armor on him, that his neck would be open like that. I think either the neck should be covered with more armor, or there should be other open spots like the elbow pits and the back of the knees/torso....something to make the outfit a bit more even throughout.

Also, the characters back seems a bit plain atm...maybe with the oxygen tank/jetpack that was suggested before, or if your caracter doesnt need either maybe just a few decorative grooves???