So I watched the video, and it looks really nice. The artwork is great, and it looks like it's a solid platformer with good level design. Based on the video anyway.
My only thing is, I can't help but feel you're limiting yourself by tethering it to the Sonic universe. Especially since Sonic isn't actually in it, I think you could have a real good original platformer. Your characters all look unique enough, with I guess the exception of the purple girl having spikes on her head. The other two don't really look like they belong in Sonic. If you replaced some things: Their running animation to not look so Sonic-y, change the rings to something else, change the springs to something more unique, change the item boxes, etc. Things like that. I think if you change a few things you could change it to a Sonic fangame with fancharacters to your own awesome original thing.