I'm quite amazed that my jaw didn't hit the keyboard when I saw that picture.

That background is absolutely gorgeous.

The rocks, the tree trunk, the grass on the ground, the distant hillside, the conifer forest, the moon, the clouds, and the night sky are all mind-bogglingly awesome!

Only the clumps of grass on the left of the image don't fit in so well with everything else, being the only features of the illustration besides Chomper that have outlines.
Chomper himself is fantastic as well. As others have already suggested, he looks like he is sleeping off a large meal. (It was Halloween yesterday; his trick-or-treating loot, perhaps?

)