Actually, I have never used e-books. Though I think it is great.
Books take space to keep, and lots of paper is needed to publish books.
E-books doesn't take space, and what's more, it is easy on the environment.
However, as Akane said, things that we have from long long ago are very valuable.
Not just books but also newspapers, or radios.
I thinks your eyes will get tires if you read things on screen for a long time, and it's true that it saves paper, but instead, it uses a lot of electricity.
Also, I'm not sure if the writer of the book will feel good if their story is read on screen.
I think it's a great idea but I hope paper books will exist forever.