Like Chesil, I tend to read one Kindle book for every paperback - especially as I have a mound of real books to get through and I'm worried that I won't every read them. But I love taking the Kindle around with me. When we occasionaly go out for a drink and OH is standing at the bar waiting, I'll have a quick delve into the Kindle.
My only criticism of the Kindle is not being able to "flick" back through easily like you can with a paperback. I might suddenly want to check on something and with a book you just flick through the pages, but with the Kindle it's not so easy - I suppose now someone will tell me how I can do that!