The art of the book, the feel of the book, the weight of the pages in your hand, how you turn them over, how you can dart from one page to the text. The texture of the wood pulp, the sound of the binding as it cracks with the opening, the slick feel of the cover, the smell of it.
You can't get that from the sterile world of the words on your computer screen, your phone . . . anything electronic, anything with a display, kills the love of the words for me.
Yes, I write on a computer, but only because I love the writing and the words come faster and I can do many more things than I can in with a pen and paper, but I will say for the actual production of the completed project, the novel, the poems, the whatever - it is only the book for me.
Bah on Kindle! Bah on any sort of downloadable books! The only downloadable book that should be on your cellphone, iPad, or whatever else you use to keep with you, is the Bible. That's the only book that you need to be able to have with you electronically, because you never know when you're going to need to open up and retrieve a passage.
But anything else . . . paper, definitely, the only presentation suitable for the written word.