Wow, this is the most non-generic skeleton enemy i have seen in a while.
I think that in the animation, when the far foot goes back, it's too high and not far back enough. i'd keep the foot on the same horizontal plane, and have it move farther back than it goes currently. Other than that i'd say it looks really nice, the head motion and the shoulders/arms are awesome. (maybe make them swing just a little? they look kinda lifeless.)
edit: oh, oh, also, when the shoulder goes down, the opposite foot should be forward. That way it will look more like a slouching-walk rather than a dance. (if you try walking in this fashion, you'll see what i mean.
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