Looks really good. My only complaints are about the hands. It's hard to tell for certain, but I think the hands are supposed to be pointing outward slightly as though Sonic were gripping a bent bar instead of a straight one. Also, the right hand especially needs some work. His thumb needs to be on the side closest to his head. Perhaps you should try drawing the vines in MCZ or the bars in WFZ to see whether Sonic grips them properly with your sprite.