I enjoy how fluid the gif is and your art style, I also like how you added a shadow below the mouse. I really suggest you don't make the head and feet 100% stiff next time you did something like this. I know it's a cartoon, but it would look a lot better if the rest of him was effected by the motion he was creating. Adding a little bounce in his feet and head would really make the motion seem more natural and lifelike. I also feel that the arms jump a little too quickly. Lastly, I'd work on your line quality. The lines are a bit rough looking. This would look a lot better if the lines and color were smoother and less pixelated.