Thanks guys--these mistakes are easy to see now that you've pointed them out! Ellian, the knee does bounce, and Sai--you're right, the other elbow should be visible on the far side. 

I've spent some time looking, but.. How do you all get the correct speed for your GIFs when you post your work? I'd love to know.

 It could be way faster 

You should add an elbow for the other side in one or two of the frames because it looks like his other arm disappears entirely. There is also a pixel error around the nose in one of the frames.

They see me strollin', they hatin'... 

Eheh. Good thing you made it this slow, it'll help for criticism.
On the leftern part, when the leg is doing bent - streched - bent , it looks like its knee is bouncing back and forth. 
Sorry if that is not clear enough, I'd like to make an edit out of your gif, but I'm at work. :(

Oh, and it lacks a tail ! :)