Great Game, under many aspects
Great game, overall.
Graphics: 8 - character/enemies are very well drawn, and the blue light effect on the sword swing is just awesome! decent backgrounds that could be more polished and varied
Style: 10 - style is, well... very stylish (in a sort of "ancient japan"-ish way)
Sound: 8 - the idea of singing birds as background is simply ingenious, but then again, some music comment in the intro or in given moments of the game (e.g. before a boss fight) would have added a lot
Violence: 8 - just the right amount of it
Interactivity: 10 - controls are very smooth and accurate, you did a very good job here
Suggestions for improvement:
1. it was a bit short, make it longer!
2. it was too easy to beat... you have a really good control system, now develop more effective enemies' AI with blocks or dodging ability
3. with all this "style" in place there's no story, just a guy fighting. develop a story around your game: part of it should unfold during the game itself.