I have no problem with the idea of making Sonic look a little chubby and 'cute' (even morso than Classic) at all. I quite like the new take on him as you've done here. You're sprite could use numerous things though to fix it. You have the highlights and whatnot but they convey no depth whatsoever and are mostly just balloon-like highlight circles, the slightly lazy way of using your brightest shades. Use your lightest shades to convey depth, it can be just as strong as the darkest one when it comes to it (It's currently making your sprite look flat).
Secondly, you seem to be banding with the second shade of peach everywhere possible, not helping with the flatness, and wasting an opportunity to add depth to the most important parts that shouldn't be banded, like his belly. The eyes are squarish and look a little weird, and his 'eyebrows' look like he's questioning someone, and don't actually wrap around the top of the eye like they should, going completely horizontal.
Both of his legs look like they're going behind his belly, and the hands and socks look undefined (if you remove the shading/AA they'd just be blobs); his thumbs-up hand looks more like he's holding a hotdog instead. For things that are hard to convey at small sizes like this, make them more dynamic and readable as possible (dynamic doesn't mean making it look complicated, sometimes just angling the part a bit makes it a bit more interesting. The shoes are surprisingly lacking any highlight unlike the rest of the sprite whatsoever. The ears are also a bit small and look odd going in polar opposite directions contrary to where he's actually facing.
It also seems you didn't take the palette to it's full potential... I dunno. Be creative with the limited use of colors, I took a Knuckles Chaotix approach and even used white as a complete shade for the peach parts. (although giving it a dry high contrast look).
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An example of all my crits on it in one edit, keep in mind it's just an example and you don't have to go by it; it's just what I imagined the sprite to look like. These are pretty good for first sprites, but moving to simple things like Kirby like all new people try to do just won't cut it or help you at all. All it takes is a ball with eyes.
EDIT: SATURATION AAAAAAAAAAAAAAAAAAAAAAAAAAAAA
Secondly, you seem to be banding with the second shade of peach everywhere possible, not helping with the flatness, and wasting an opportunity to add depth to the most important parts that shouldn't be banded, like his belly. The eyes are squarish and look a little weird, and his 'eyebrows' look like he's questioning someone, and don't actually wrap around the top of the eye like they should, going completely horizontal.
Both of his legs look like they're going behind his belly, and the hands and socks look undefined (if you remove the shading/AA they'd just be blobs); his thumbs-up hand looks more like he's holding a hotdog instead. For things that are hard to convey at small sizes like this, make them more dynamic and readable as possible (dynamic doesn't mean making it look complicated, sometimes just angling the part a bit makes it a bit more interesting. The shoes are surprisingly lacking any highlight unlike the rest of the sprite whatsoever. The ears are also a bit small and look odd going in polar opposite directions contrary to where he's actually facing.
It also seems you didn't take the palette to it's full potential... I dunno. Be creative with the limited use of colors, I took a Knuckles Chaotix approach and even used white as a complete shade for the peach parts. (although giving it a dry high contrast look).
.
An example of all my crits on it in one edit, keep in mind it's just an example and you don't have to go by it; it's just what I imagined the sprite to look like. These are pretty good for first sprites, but moving to simple things like Kirby like all new people try to do just won't cut it or help you at all. All it takes is a ball with eyes.
EDIT: SATURATION AAAAAAAAAAAAAAAAAAAAAAAAAAAAA