We've used a similar corner shelving unit to create space in a small 7 by 9 ft room. It's a great, easy shelving solution for small spaces (although installing it was a bit tricky as the walls weren't plumb.
Way easier than building one of these book cases! Some cute fabric and a double-poled curtain rod. Instant place for books in kids room and can match fabric to their room theme! Would be great in a kids book nook