The controls could be easier, W for jumping and L for triggering skill moves, for example.
The walking/running animation is not nice. He looks like he was running, but then again he just moves an inch.
Enemies are too stationary, you could work up their brains.
Other than that I would suggest improving by transforming this into a more serious Beat-em-up.
looks good... how do we play?
Have you played Street of Rage, or Double Dragon, or Golden Axe? If you made it like that with stages, boss fights at the end, and a story the game would then be entertaining. The story doesn't even have to be base completely on the KOF universe.