Hi DungeonDan
I love mushroom people! However, a lot needs to be done for it to look like you want it too.
To begin with, you need to have a look at the lineart(I take it, it is a lineart) and smoothen the lines a bit at the top bit aswell as just at the bottom. With the angle you got + the shapes, makes it a bit wierd.
I am also concerned about the dots and colours used. I suppose you dont want your sponge to look like it got glowing laps all over his head
It would be enough with just 2 colours, 1 for the dots and 1 for AA.
I made this edit to show you how to give it just a bit more character and to clean up the shading + colours:
good luck mate!