The article tries in several paragraphs to explain the experience of using it - I'd recommend instead just clicking on the Library Explorer link[1] yourself and actually experiencing it yourself.
There's something to be said for these physical-world-analogue UIs, in my opinion. Even if this is technically the same affordance as provided by old school web directory UIs, there's more of a sense of tangibility and immediacy to this kind of visual presentation, that makes it more appealing and easier to spend longer times in.