/agree with TheTrueFreak
Everything that I was going to say, has been said by TheTrueFreak already.
That being said, I still have to write a review;
It would have been much better and a better demonstration of your animation capabilities if you used your own characters, not Sonic characters.
You drew them really well (not exceptional, but still pretty good) and the part where Shadow's mouth moved were done really well.
But thats about it.
Having a still shot for 10 seconds while the music carries on, is not animation.
During the part "I see the girls walk by, dressed in their solemn clothes..." it is just a still shot, and you are essentially riding on the music. This part could be done much better, and have the girls actually walking, or doing something.
I lold a bit at the parts where Shadow and Knuckles were fighting over the color of the door, but thats about it.
Yes, this song is not meant to be funny, but if you have a funny part in an animation, you should have other funny parts, or the seriousness and funniness clash, and confuse the viewer, while diluting the message of your animation.
Like TheTrueFreak said, it "could be better" but for now it is just alright.