The line work is nice but I feel like you could do a little more to spruce it up

Have a look at other cartoon based graphics on the site to see how you can better represent this piece. The basics of it look good.

for something this simple, I think you need to go for really nice aa on the outline.

hes the best ^^... pixelwork could need a lot of improvement tho... probably a trace too.... maybe make him blink