Good luck putting all those wrinkles into a sprite!!!! LOL!!!
I actually do like the designs, it just has so many damn wrinkles, like, get some cream or something, damn!, dude looks wrinklier than my grandma. You'd probably save a lot of time if you didn't make your desings so wrinkly and used the wrinkles more for specific drawings, instead of being there by default, imagine animating something so wrinkly!
Also, i like the sonic sprites but the shoes seem to lack the upper part, at least in standing, idle and up looking sprites