Stuff I changed:
- Shape: You can see that on the corners, I used the old 1-1-2-4 pixels to make a rounder shape
- Less colors: You used too many colors. 4 shades is enough for a piece this size, and I made sure they had enough contrast between them, so no colors are too close
- Lighting: Over time you'll get used to imagining what's the shape of the object and how light would realistically hit it and create shadows and highlights. By doing this the shape of the object is more clear
- Removed AA: anti-alias is supposed to hide the jaggies in the lines. What you did just added some kind of fog to the edges. When making "perfect" shapes like these (straight lines and clean curves) AA is hardly needed