Not good.
Since this is your first game, you get a 1 for effort.
Same animations, sounds, background, same enemy and repetitive gameplay.
Try adding a story, increasing the difficulty as the game progresses. Powerups. Online Highscore List.
Lastly, make it so that the bad ninjas can actually hit you wherever you stand.
While typing this I positioned my character at the far right of the screen. There are over 100 enemies and none are hitting me from this position.
TEST OUT YOUR GAMES.