Jealous I won't be able to participate in this competition... I can tell already there are going to be some excellent entries.

I agree with the others on the palette working well, however, I think you should use lighter shades on the tree as it's darker than the rest of the picture giving it a bit of a disjointed air.

Very nice composition. The AA is a bit overdone, making it a bit blurry in spots and there is some banding (on the tie for example). The fox's ears seem a bit rushed, as well as his spectacles. Also, I don't like the red heart in there, although that's just my opinion. Good luck with the challenge. Edit: Also, I think you could bring the color count down a bit by merging a few grays with the browns.

Would love to see you try out animation with this style.