title_body: Ebook content versus physical book content
upvoted_answer: They are actually two different questions :-)
  
  In Europe, for example, sales are affected by the fact that (paper) books have a very low VAT on them (in Italy it's at 4%) while ebooks are taxed like most goods (in Italy it's 22%), so it may even happen that an ebook is more expensive than a book. 
  
  As for readability, my impression is that it heavily depends from the type of book. A novel, or in general a text with few if any pictures and which is read sequentially, is equally readable; for non-fiction books, where people tend to skim content, to return on a previous section, or to peruse the notes at the end of the book, a physical book is easier to read but an ebook is easier to search in; mathematics on an ebook is a complete mess, at least until epub3 will be deployed in full. 
  
  I read on Big Data: A Revolution That Will Transform How We Live, Work, and Think that Amazon actually collects statistics on how people read on their Kindles, but I don't think the results are public ;-)