Thank you all for the constructive comments ^^
*broke the symmetry on the books
*desaturated the distant shelves a little more to divide the picture in 3 planes(table, bookshelves, distant bookshelves)
*made some more interesting books (including a massive book that needs a reinforced shelf)
*decorated the books shelves a little
*made the character less chubby
learn, learn, learn, learn, learn, learn...