How in the world is Apple going to keep textbooks up-to-date and not lose your highlighting and note positions?
Did Apple come up with some magical new way of marking the beginning and end of the highlight area? The obvious way is to store the start character position and length (or end character position). But what happens if a word changes before that section? Do they, in essence, track changes and figure out how many characters to adjust the highlight position? What if a word changes in the middle? Do they know where it is and can adjust the highlight length? What happens if the entire passage you highlighted is deleted by the author?
Or do they do what Amazon did: throw away your notes and make your start over? (Bad. Very bad.)