Very good
I have not noticed any glitches, as my machine has the fully updated flash. It also generally plays everything I try, so it might be hardware problems on people's ends, but I do not think it is the game itself. Just try to update your flash peeps, and if that doesn't solve it, then your hardware is messing it up. It is not the game.
As for the game itself, it is very fun. I don't like the keys for the action/jump/attack and I frequently mistook one for the other, but I kinda got the hang of it after a while. Might try a different key set or allow the player to choose between different key sets because I know some people would like WASD better than the arrow keys. Might make attack the space bar or something and use would be E.
The graphics are good as well as the story, and like I said earlier, I did not notice any glitches. Good job!