Nice
Random suggestions:
-- Make the belt curve around the penguin's fat belly, to give him more volume
-- On the feet and beak, you're basically wasting a color. The two shades of yellow look the same when it's zoomed out -- maybe try a darker yellow?
-- I know you're not done shading, but I'll crit it anyway
The belly looks like it's shaded directly from the front, but the beak looks like it's shaded from the top, and the rest of the piece isn't shaded at all. Pick a lightsource and shade *dramatically*, with darker shadows and brighter highlights than you think you need
Contrast covers a multitude of sins!
-- You might try some less-saturated reds and yellows, to make the feet and clothes blend into the piece more
-- Bigger hook!
Overall I think the lines are cute and it's coming along nicely