One advantage of an e-reader is that if I wanted to buy a copy of an old, obscure book, like Varney the Vampire, it would cost me about £0.01 as an e-book or about £30 as a paperback.
A disadvantage is that I enjoy looking around bookshops. I nearly always see something I would like to read. Thanfully, I have some willpower or I would have a five year backlog of books on my shelves. You wouldn't get that if all there was were ebooks.
I don't trust them anyway. I was burned by my experience of my iPod.