Disclaimer: I really really like this piece. I love the 'cuteness overload' thing, which is probably why I have so much to say about it. I think it has great potential, so please bear with me:
It looks too monochromatic IMO. I know it's supposed to be the North Pole or whatever, and everything is blue, but why does the penguin have to be blue? Why does the fish?
You planned out some hue shifting on the background and it's a good start but... I really think you need to kick it up a notch or twelve to make this piece more stylish. How about an Aurora Borealis in the background?
And I know it's a bit cliché in Icy stages, but how about some precious gems encrusted in the ground? Too cliché, never mind... The penguin looks somewhat humanized, can it speak? Does it live in a little house, in a little igloo? Does it live with other penguins in a cute little penguin village? Why not add that to the background?
Also the face of the penguin looks a little off, the beak should be larger and about 2 pixels higher in the face.