Not the best.
Basically, this game looks as if all you did was make on huge tween and when the character pressed right, the movie will play, and the tween will go. And the enemies just look like movie clips that come in when you reach a certain frame, an enemy will come in. Also, the music wasn't the mest either. It was too heavy, and it just didn't fit the mario STYLE.
Also, the tweens took too long and everything was too slow.
It was okay, but it needs a bit of work. Like instead of using on(key), I would use if (key.IsDown(39)), so it would appear smoother.
It was a nice job though!