It's a nice model so far, but could be far more detailed, in my opinion. Specially for such an expressive and cartoony design. I think the eyes could look a little angrier and have pupils too. The top of the head feels too round, and the mustache feels rather flat and short. Another thing bothering me is how the body is a perfect sphere, it feels like he should have something lightly more egg shaped.
If it helps for reference, you can use my old SRB2 Robotnik sprites. I had like one or two animations ready for him, but he ended up canned because I didn't really like how the shading came out, and would probably remake him completely if I ever wanted to bring him back (which I really don't feel like doing, as much as I love this design)