Your best one yet, always getting better! Keep on it man!
That's the best attitude to have :D
Looks great, an instantly recognizable character. My only crit would to use more of that white to your advantage, since he's metal there would be a lot more light bouncing around (though perhaps that would take away the clean style). Also since he's cylindar-ish there would be a bit of light seeping around and hitting him on his back. Looks pretty great!
@gogglecrab: thanks!