I don't use e-books, at least not yet. I like to hold the physical book in my hand, but I can see how an e-reader could be useful. In fact one of the high schools around here is thinking about using an e-reader for the text books for certain classes. The aim is to reduce the load in a student's back pack...which in it's own way, makes some sense.
I actually bought an early Kindle. I am not a huge fan of it. But I do like to read on my phone. It is very convenient to read 5-10 minutes at a time. The Nook and Kindle are just too big.