I don't LOVE the rug. but I think the green curtain, built-in shelves filled with books and the (presumably) sliding ladder are wonderful. Its missing a fire place, lots of cozy blankets and an oriental rug!
Small Space Secrets: Swap Your Bookcases for Wall Mounted Shelving. Here's a creative shelving arrangement that uses a deeper shelf at bottom to create a sort of bench. The bench can serve as extra seating for parties, or as a display space.