This was a cute idea for the challenge. I think it might be improved with some diffused lighting -- the flash appears to have created harsh shadows in the background and blown-out shine on the faces. I might also suggest getting parallel with the characters instead of looking down on them. And finally, I'd crop it a little closer. Hope this is helpful :)
Great concept for the Holidays, I don't see anything special, the b/g goes nice w/ the subject, the lighting on the faces seem a bit harsh, maybe try to soften the light up and it could inprove