Yes, that's looking better already. I think you only anti aliased way too much under his ear, so I recommend you make the shading in there less exaggerated. I also would make the vertical stitches in his shoes a little more subtle, as right now, they feel way too distracting. If you can, try also using darker colors from the palette for the stitches in the shaded areas.
While still talking about his shoes, I noticed that it doesn't has as much detailing as the rest of the body and the front sprite do. The red outlining does needs some darker pixels here and there and so on. Do not worry about borrowing colors from the front sprite to detail the reds and whites of the shoes in there.
Looking at the ears, I see you applied some green around it. It works for his left ear (the one on our right), but it doesn't work so well for his right (our left) one. You see, from this angle, only the back of his ears would appear, so only the back of the ears should have some green in it. In his right (our left) ear, I strongly recommend you change the green outlining back to the grey you had before.
Minor nitpick, but one of the eyes feel a little bit like they're kind of jumping out of his face. You might want to try keeping it a bit more in his face by outlining/shading a bit around the part that's near to outside his face. For another little nitpick, see his right hand (on our left)? The placement for it is very fine, but for it to look more natural, you will need to move the bottom half of the arm one pixel to the right, and smooth things up from there.
And one friendly warning. See these pixels?
You will want to use avoiding these specific colors, because while it might seem just like normal shades of green, they're actually not part of the green palette of the game. They're actually part of the Zim palette that the game has, and keeping them in the sprites will make them not change into orange or any other player skin colors while added into the game. Be also careful to not accidentally end up including Neon Green into the sprites:
You're certainly learning well so far, and I can tell you're slowly improving. Keep up the decent work!