I like the cartoonish design.
I do like the cartoonish design you have here, but there are some things you can improve on.
Your shading seems to be all over the place. Where exactly is the light source for this picture? The placement of your shading seems completely arbitrary. And if this is just a simple little cartoon, you might even be able to get away with foregoing shading altogether and leaving things flat.
One thing you might want to try is using thinner lines. While a lot of cartoons do use thick outlines, the thick outlines are only on the outer edge of the cartoon, and the inside details are made up of far skinnier lines. Look at the character design of "The Fairly Oddparents" for example. It make the cartoon look a lot cleaner and a lot less muddled.