I dunno, this looks like a good idea on paper, and I think it looks super cool, don't get me wrong. But I think those books would get tore up if people are stepping over them all day, every day, toes knocking into them and stuff. Plus, and don't quote me on this, I think that the length of the step isn't exactly to code.
A ton of clever hacks for small homes and apartments! You may find that you need less space than you think. :)