Well gosh do I love robots! Now, i'm not an expert at this "art" thing, but I do hope you take this critique as if I WERE good:
- I like how you've put in more geometric shapes and forms into the character, yet some of the linework is wobbly funky fresh (Which is a problem I have too, unsurprisingly).
- The balance in this picture is what really throws me off. The overall design of the robot is good, but the legs are a little too far back and far-reaching to the rear that it looks like he's going to tip over! Especially with the gun in his right hand that's held out AWAY from the body, it looks like this dude is going to fall. One way to fix this, in my opinion, is to "widen" the leg room. If you increase his "stance" and sort of widen the space between each leg, make him in a deeper squat, then the picture would seem more balanced. Also, having all that negative space in the area below his gun and by the right leg is really good at drawing my eye to it, and that's a "meh" situation. Oh, and the feet are a little too small for this guy, perhaps making larger feet would make a more balanced character?
-My final, annoying, un-needed point is about the shading. It's pretty easy to see in this that you HAVE colored in some of the character. However, a lot of the picture is still in need of some sweet sweet shading n' lighting, like on the what-I-would-assume to be the armored parts of said robot.
Overall, sorry for my incessant nagging n' such. I feel super guilty for making long posts like this, but I feel this robot could look way better when some more principles are properly applied!