Honestly not as good as all the praise makes it out to be. Mario's jumps have no momentum after letting go of a directional key, you can't kill enemy's by running into them with a Koopa shell, Goombas have Red Koopa motion patterns, and when you try to zoom in the webpage to make the game screen bigger, the player zooms in irreversibly. Not worth the trouble of dealing with.
(Short/useless comments don't award GIPS)