Are they shaded in any way? Can't tell due to the size, if they are shaded I would recommend using more contrast between hues, think the latter NES games. That would make him awesome!
I like the run/walk animation! Incidently, that animation could work either running or walking - the character speed wouldn't matter too much, it just adds to the cartoony look of the character. Maybe it might be worth experimenting with little dust clouds everytime his feet hit the floor, just to add to the effect? Nice work