exactly what i was thinking

It's a very stylized form of animation, and I like it a lot. I think _Connor is talking about the transition to a backwards foot, which because of the low frame count might look odd. That being said, I think the exaggeration is part of the appeal, and the joints seem fine to me.

The background is really nice too, even though you only see a tiny bit of it.

 Where exactly do you mean? What part? shooting or jumping? I exagerate a lot but I dont try to break any joint.. Sometimes I make straights going curve to follow the movment if you get what I mean, but I never make impossible joints movements (I try at least).

 Im flattered that you meantioned Earth Worm Jim.. I know, its a lot chopped, I actually gave up at some point, but I still find it cool thou.

 Why do the feet bend impossibly inwards? that pretty much throws the whole thing off for me. :|

 Ir reminds me of Earth Worm Jim. And I agree with Rayo, this would look much better with some more frames.

You should add way more frames to make it make it much more fluid.