Looks pretty good: my only criticism is that the shading is very ragged on the wings. The easiest way to fix it would be to first zoom in and make it symmetric, then either use a blur or smudge tool on those regions.
(If you aren't using something with those tools, I recommend GIMP - once you get used to it its nice (and free), although no photoshop from what I here.)
I like the overall shape and the decal looks nice! Hmmm... maybe once in the game it will be too dark to see the decal well? I dunno, but if that happens you might need more contrasting colors.