A pretty good first pass. All the above comments are definitely good ones. My $.02 is that the robot needs some 'weight". Right now, it looks like it's made of paper! :-) The "follow through" movement after the kick and other secondary movement will be a good place to do this. Also, maybe the leg lift prior to the kick can be a little slower, or have an "ease in" effect. Remember that your character would have weight in real life, so anything with significant weight (ie a robot limb) that gravity would affect should be animated. Keep up the good work! Carry on...