First poster here, eh? Well, I have to say that I like what you did with the wings in this. They're very creative, and they contrast nicely with the fact that the girl is holding a scythe. The large moon is an awfully strange position for a wallpaper, though that's actually nice--something rather unique. It further draws attention to the focus, by putting it lower than the focus, which is nice. I'm not terribly fond of the blurred star background outside of the gate, though I like the idea--it's very creative, and again puts focus on the girl.
What draws me so much to this wallpaper, though, is the nice use of contrasts--contrasts of ideas, contrasts of colors. The girl that is the focus is all in white, which contrasts largely with the fact that she's holding a scythe, as well as the black cat in front of said scythe. The cat in and of itself offers some interesting contrasts--a black cat with angel wings and a halo is an extemely interesting idea. The contrast between the two black moons and the light colors of the focus of the wallpaper are also quite nice. And then there's the contrast between the starry background outside of the gate, and those inside. If you'd used less stars, I'd like this a whole lot better. Nice job!