I prefer the coloured body panels to the outline. The yellow was a bit wishy-washy and the outlines looked cheap somehow.
The feet look a lot more interesting too. Good work.
Not sure about the horns! Unless they make sense in the context of the story they seem a bit odd on a robot, to me.
At this stage, I would probably go round your clusters and tidy them up. Give your clusters "nice" shapes. If they're representing a curve, remove jaggies and give them smooth steps. Try and remove single pixels or stair-casing. Try and favour 45 degree diagonals, vertical and horizontal lines over other angles. Obviously you can't do this everywhere, but where you can. At the moment the robot has a bit of a rough feel to it, but I think with a little detail work you could really make it shine.
Once you have nice cluster shapes you can add more specular effects or pinpoint highlights.