e-books vs tree-books

Don't get me wrong I LOVE the idea of an e-book.  I've often considered buying an e-reader or tablet and putting the app on it.  I have read the odd few pages of e-books on my android smartphone but it is so small that I could never read a whole book on it... we do read e-books on the internet occasionally (small few page ones),  and of course when you want to read 'that type' of book on a bus load of people an e-book is so much less embarrassing :).