I think the walking/running animation for your other sprite is better done than this. It looks choppy and it seems to focus more on the forward movement of the legs, where in real life the focus should be on the push off of the ground. If you have ever done sports or exercised in general, it looks like your character is doing "high knees". I would also recommend maybe having the gun move as the character is moving. It will add more fluidity. I like it though and think it is a good starting point. :)
Oh, well in that case it is well done! :P