The artsy-ness of this image makes it tough to tell, but I think those are wood walls with each plank stained a different bright color. Or it could be a pastel drawing on the walls. Either way - Totally cool. (Have tried desperately to find where this image originally came from with no luck. Obviously from some magazine.) (Oh, the polar bears are cool too!)
If you have a high ceiling look what you can do in that bedroom. Use the top bunk as a indoor tree house for the kids reading nook. Decorate accordingly for boy or girl. Notice the chandelier that has been covered in silk vine. Use camouflage material for a boy's reading nook.