There's things that digital books will never be able to do. The hefty feel of a book's weight in your hands, the neat rows of books standing in a shelf, the smell of printer's ink and paper, the beauty of a well-executed binding.
The way a well-loved, often-used book falls open at favourite passages. The little scars and blemishes and tiny drops of tea and tomato sauce that attest to a book's being so captivating that you had to keep reading even while eating. The fact that you can glance at where you are in that book and get a little sad that you are already halfway through... Books, real, physical books are a wonderful thing.
However, that's regarding modern books. Books that are in print, and that you can get easily. For manuscripts, though, I will sing a different tune: Manuscripts are rare, and precious, and hard to gain access to, so I am happy for every single one that gets digitised and put online.
Such as the Stuttgarter Psalter. Or the Utrecht Psalter. (You can even download the latter as .pdf, which is just wonderful.) The Codex Manesse (also downloadable).
In case you are wondering why this comes up now (again) - I am leafing through manuscripts looking for depictions of spinning women (or men, I'll take them just as gladly) from before the 13th century. Any hints, links or pictures are more than welcome!