You have a good idea but...
It somes some kind of background music. Something fast, but oriental as well. You put power rock in there and it will ruin the feel for the game. Also, a diffenrent method of slshing would be better too. All I had to do was spin my mouse around my samurai and I become a human lawnmower on a horse. The graphics are pretty good where they are at. You may want some kind of little cut scene like showing the samurai standing atop a hill, then riding down to put the fear of God in the villagers.
This is a great game start, it just need a little polishing.
Oh, and put a little more story to it. It's kinda dry just killing endlessly and jumping your horse.