Definitely awesome for a first try. Since you want to know, here are the wrongs and rights I came up with.
Wrongs:
-Too choppy - Try increasing frame rate, and adding more frames.
-Too slow - making the animations move quicker increases tension and makes it feel more action-like.
-Scenery - The backgrounds are a little unscaled and doesn't blend with the characters. Try creating your own.
-Music - The music didn't really compliment the actual fight. Either that, or add in sound effects.
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Rights (in my own opinion)
-Art - I enjoyed the sprite theme. The effects you drew are good too.
-Concept - Although a little story/dialogue entry would have made it start with meaning, the idea is pretty good. It's common enough to be understood easily, yet very flexible because of fighting possibilities. Definitely excellent to start with, I think.
Hope this helps you out to make improvements :D
Looking forward to seeing new videos. Good luck!