Now, a shelf like this, covering a wall from floor to ceiling would be pretty clever in a small flat. Tons of storage and room for fancy stuff, but you could also place furniture (like a sofa) in front of it if you want to.
Rows of matching Billy bookcases from Ikea work well here. Consider that the books and accessories offer the pop while the bookcases provide the background. (contemporary living room by Smith & Vansant Architects PC)