Pretty amazing.
You're effects are beautiful, the storyline rocks. I can't say much about the sound, because my speakers are broken. My only critiques are that you're bending the characters' personalities somewhat. Sonic seems too serious, Amy isn't acting ditzy enough. Tails needs to be a bit more naive. Also, You shouldn't bend the rules so much. Sonic shouldn't be able to transform into his super form without the seven chaos emeralds. But still, this flash is highly entertaining and very well done.