This is one of the handiest studio gizmos I own. Actually this is the smaller cube- I have a much bigger one that is best for photographing larger items. In my part of the country, relying on natural light isn't always an option. These light cubes improved the look of even my point-and-shoot digital snapshots so much, that I was a convert after my first try.
If you are interested in taking great photos of your books, I recommend Laura Russell's blog, found here. Laura is the owner of 23 Sandy Gallery in Portland Oregon, a great place to visit if you get a chance. And her blog entries about photographing your artist books are simply the best.