I have had a number of students I tutor over the summer use tablets. Here are some things I have noticed.
First, not all tablets are created equal. Some are much easier to use than others. On some you can highlight in different colors and make notes, on others you can only highlight in one color and some don't let you make notes.
Second, tablets make it harder to flip through to look for something. On the other hand, you can search. However, some people are visual. They know the approximate location of something in a book, and can't search because they don't know what they're searching for!
Finally, one of the best things about tablets is that you can load multiple books. However, going from one book to another can be harder on some tablets than others. It's also harder to share books.