Currently, I have a toddler and an 8 and a half year old and this system works for both of them. My oldest is familiar with how traditional book organization in libraries works, but she knows that at home we organize our books by color. She also happens to be dyslexic and I think that organizing the books by color is a great system for her as authors and illustrators don't necessarily register as strongly with her.
Now that I've had these book ledges up for a over a year, I can't imagine our home without them.
They are very reasonably priced ($9.99! for a 45 1/4" ledge) and have held up very well. My only little criticism is that I wish the screw covers were more substantial than just white stickers, but with all the books on our ledges I never really see them and at that price point it really is something to easily overlook.
These lovely book cradles are generally in my kids rooms, but I put them in our playroom for March so that we could all enjoy this book rainbow. My father in law made these shelves for us after I showed him these at Book/Shop. I love this way of storing books for multiple reasons, the easy accessibility, the fact that the books spines are happier (I have some of our books stored horizontally and I've noticed that it is harder on their spines over time), and because they let my kids have a collection of favorites in their own spaces.
How do you feel about organizing books by color? I know some people aren't fans, but I have been doing it for years and I love it, so does this guy: