It looks cool but could use some work, as the above posts say, make him look less chubby seing as he is adult now! Also what id say to make the head better, keep the current width size but make the heigth like 2 or 3 pixels more (change from somewere at the cheek. Anyway, i havent checked the animation in any animation program but, it looks to be good! Anyway overall its pretty good, keep polishing and you have a kickass sprite sheet!
Regards,
Norlem