Tight
Plotline: Getting better and better, 9/10, but I do wish Sonic would just shut up about Amy already. It's been a year already, and sometimes the way the characters act makes it seem as if it's only been a few days.
Animation: 10/10 Incredibly smooth. Astoundingly smooth. Even the backgrounds were animated.
Sounds: 6/10 Sound effects were slightly overused, and some of the background music just didn't seem to fit. You made me happy by using 'His World', though. Gotta love that song.
Specifics:
*The battles could be less monotonous. The characters use the same sets of moves over and over again, so it can get a bit boring.
*The times you used drawings (or maybe they were pixellated, I couldn't tell) really fit in with the animation. Good job with that, I hope to see more of it in the next installment.
*I was hoping that Sonic was actually working with Shadow the whole time, but oh well. Metal Sonic's still cool, too.
All in all
9/10
5/5