You don't know how to draw a head. But You can always work on it.

yeah, get rid of the black outlines.
try lowering the color count, this one looks pillow shaded.

The background is really awesome looking in my opinion, but the black outlining does have to go, just like Ensellitis said. If you smoothed it out with some light AA, then this piece would really shine~

I quite like the sun. Is it a reflection in water or just a hazy armosphere making it like that? The sharp jaggedness of it make it looks like a water reflection.

I don't think the way you've shaded the person's head takes into account the environment's lighting conditions. I'd recommend adding a thin orangeish highling on the right hand side of the outline because the other side of his face would be lit up by the light from the sun and the light would scatter through his skin. Check out this great lighting tutorial, it should help.

I really do especially like the way you've done the sun though.

i agree with ensillitis, but im no good at sprite art so...

sorry, but the black outlines ruin it, try using a darker color of the hair/skin.  sunset looks pretty good