Back in 2006, I mistaken this for a full episode of Sonic X & it was my first exposure to Newgrounds.
What I think about this Sonic related flash short nowadays? I honestly think the animation could've use some improvements such as not relying on tracing screenshots or concept art from Sonic X, making sure the character's proportions are on-model at least, improving the waving quill physics (plus Sonic & Shadow should have six quills on the back of their heads), & improving the backgrounds by not heavily rely on gradient effects & trying to use different art tools that work best for you.