Seriously, I think that's the problem here, the black lines that you've used everywhere. xD Screw 'em, just go without the outlines and such. On the emerald, it'd look a lot better if you replaced those dark lines with extremely light/dark green/yellows, to make it look shinier and more awesome, and on the rock outcropping holding up the emerald, just use dark browns, and on the stone predastal/contruct and wall thingy, just the darker shades of the off-white colour. And Knuckles certainly doesn't need those outlines.
BUT THE BLACK LINES FLACCID; THEY ARE MY SAVOIR *baws*
Yeah, I have to admit I'm too dependent on them... XD By that you mean the use of colored lines, or no lines at all? I think I've done the former before, just without success..
I just want to apologize if I fail at taking critique outside of my realistic art projects, since on most of these I just get 'COOL' spammed on them, so... Yeah, not used to them. I always appreciate them though!
And oh, I forgot, rather than the black lines on the rock supporting the ME, you could replace it with a faint green light. I know you've already shaded it, but this is just an extension of the whole no-lines-whatsoever advice. xD
Well, a mix of both, really. As in, if you have to use a line (say, to draw a mouth) use the appropriate colour, which in the case of a mouth would be a brown that's near-black, but aside from such things, methinks you'll want no lines whatsoever.
Meh, I don't mind. xD Me critiquing others' artwork helps me to identify the mistakes in my own as well, but I certainly hope you use it. XD Even if it is on a Sonic piece. ;D
IN ANYCASE, I DEMAND AN ABSOLUTELY LINELESS REVISION OF THIS PIECE, IMMEDIATELY. D:<