Good work... but lacks something
Don't get me wrong, I liked the collab, but it could be done a lot better.
Instead of all the classic scenes where Sonic fights with Shadow and turns Super Sonic (Boooooring...), where Super Sonic fires a beam of energy (Booooooooring x 2...) and those ripped images from Sonic X (that's not boring, just pretty lame), each of you could have done a little story, like the author who made the piece where Tails rescues Knuckles or Shadow that fights the G.U.N (those are the 2 that I liked most BTW).
I didn't like the drawings of some authors but I understand that Sonic & Co. are pretty difficult to draw, ever more difficult to animate, so I'm still giving a 9 to the graphics.
Keep up the good work, although I would appreciate more a story rather than a small collab. Oh and please, if you do one, don't put any Megaman or Matrix cross-overs, those things pretty much suck :D