too boxy on top of the just barely pixelated sprite. the sprite is too out of focus when compared to the background, brings your eye away from the focus object. colors dont match...
and the focus object is like... half a centimeter too far to the left TT_TT if you're gonna put it in the middle, its gotta be in the middle or else it just looks sloppy. and is he smeared? it kinda looks like he's growing his hair out. sprites are too small to use that fx on.
not enough flow between the bg and the fg (background & foreground...) its just... a background; a foreground; and some light.... needs interest!
text needs work
background is too detailed to be opposing a sprite.

overall its good. i dislike sprite sigs tho, so my criticisms are gonna be hard sorry D:
i like the bg, it looks good, just not for this.
to a passerby, it doesnt look half bad, but when you take 5+ seconds to look at it, you notice everything.

since its your first tho, you did an amazing job

8/10 ^.^ keep up the good work