Agreed, the UX of paper is still so much better than kindle. Nicer to read, no lag, easier to organize and share, nicer taking notes in margins. I bought a kindle and went back to paper.
There's also longevity, which ties in with search-ability. Modern paper even under the best of conditions only has a century of shelf-life, where as digital data should persist for forever. Also as it's digital we get the benefits of flowing text, searching/indexing and easily converting to new formats and even languages - and the ability to easily update these conversions as technology progresses.
Theoretically (on paper?) digital books have all the benefits in the world. As a book lover I still can't quite get on with them in all but the trashiest of uses.