Technical books in print are generally better formatted than their e-book cousins (O'Reilly's digital library, Kindle) unless they're PDFs. This has a major impact on readability if there are significant amounts of diagrams or code samples or tables in the text.

I've also found some physical books nicer for reference then their digital versions.

I sometimes think 'I really prefer physical books, if only they had Ctrl-F' - but actually, in reality, it's often so much easier to leaf through and find something (from rough memory of where it was, skimming, jumping around, ..) than it is to search digitally (get the search term right, see results with little context, find it's impossible to search for part of an equation or the text in a diagram, or oh damn it was rendered as an image).

When something isn't just flowing text, it can be a real crap shoot in ebook form. And, even if the formatting is fine, I often find technical or other reference books (e.g. cookbooks) generally work better in physical form.

I much prefer physical books to e-books, especially for technical ones. I learn much better from a physical copy - flipping back and forth, checking where the current section fits into the bigger structure etc I find to be easier. I also like to underline and write notes in the margins - again, I prefer this in a physical book.

I've found few issues on which people are as diametrically opposed as the ebook/physical book debate.

I did a reading group at work a couple of years ago (for Designing Data Intensive Applications as it turns out!), and half the group looked at me like I had 3 heads when I offered to buy them hard copies and the other half was insulted if I didn't offer them hard copies

Trees are a renewable resource.

For sure, but my shelf space isn't.