I like the design. Although both simple it has a complex feel about it. Especially around the hips and ankles.
Some of the areas lack some solid definition where others do not. The sockets on the upper arm and at the elbow kind of show what I mean. Compaired to the top crease at the top of the thy or the creases i nthe ribcage, I would expect those joints to have a more solid contour.
Other than it being faint in a couple of areas, I do like the line art over all. It is thick and dynamic. You have some pretty solid line weight.
Your coloring and lighting are pretty nice. The blue glow is a nice touch, although I wish you would have pushed it a little farther, but I'll get to that later. The coloring along with the shadows are nice and subtle. it gives this a very smooth appeal that one just can't help but like.
(OK Now to try and finish this review before I get interrupted again)
One thing I wish you could have played with a little more is the blue glow. I think you could have had a little more behind some of the metal plates and have it reached out and bounce on other parts of the robot.
The robot's head in his hand seems a little on the small side.
One thing that needs some mention, I noticed that part of the rib cage is kind of showing through the bots hand just a little. I it's not much, but I'm sure you'll notice it when you look for it. Its a quick touch up that should take longer to get Photoshop up and running that it will fixing it.