I loaned my pal Charles my black and white Kindle 3G for the weekend; Charles and I are both avid fans of the printed book, but as I told him, there are some times when the convenience of the Kindle is hard to surpass. A good example of a work that I enjoyed on the Kindle was the new Stephen King book; while I have a printed copy, it's a hefty, burdensome book, and it doesn't balance well on my chest when I'm lying on the floor reading (in fact, my chest actually began to hurt after a while because I kept resting the bottom edge of the spine on my surgical scar, which is sensitive to this day for some reason I can't explain). So I tried 11/22/63 on the Kindle, and found it to be a very pleasant experience. The page width is sufficiently narrow that I don't have to move my eyes from side to side at all--just straight down the page, taking in a line at a time.
Since Charles is now reading 11/22/63 as well, I figured it would be a great way for him to test out the Kindle, too. So I brought him my Kindle and the charger last weekend. He called today and, as I suspected, found the Kindle to be very handy--compact, portable, light-weight, easy to read.
Of course, neither Charles nor I are looking to replace books with Kindles--but it's a nice supplement when you want to take a variety of reading material with you, but don't want to invest in a rolling bookshelf. It's also very handy for public-domain books (thousands of titles right there for your enjoyment, no investment other than the hardware) and I find it to be very useful for non-fiction, where I'm just looking for the information, not the package itself.
I also showed him the iPad, and we discussed its advantages (larger, more detailed screen, color, a more booklike interface that has you "flipping pages" without a black screen in between page builds) and disadvantages (the glass screen is reflective, so glare can be an issue), and it's a little larger and heavier than the small black and white Kindle). If Charles wants to borrow an iPad to test it out, that's easily do-able, too; it's the best way to decide which device meets your needs, after all!
We'll see soon enough whether Charles becomes a Kindle owner...