I've been reading a fair amount -- but putting up notices on Goodreads rather than fuller write-ups on this blog. I've also been reading a lot about ebooks and ereaders -- manic and apocalyptic (e.g., Franzen), and I thought I would weigh in with my own personal experience as a reader and book buyer over the last four months (I bought my low-end $79 Kindle in October 2011).
First, a little context: I am not a book collector, but I own a lot of books. I have liked to surround myself with my books as, I suppose, a physical marker of my experience reading them. I do donate and sell some books (e.g., to Powell's) and I use the library, but I also keep books that I'll never read again. They take up space, and I've moved books several times. Next time I move, I plan to cull my collection. I like the book as physical object, and perhaps partially in response to the emergence of electronic text, I wrote about the cultural and social meaning of books and print in early and 19th-century American culture in a doctoral dissertation completed in 1997. That said, I'm not overly sentimental about books (and less so in recent years), nor excessively enamored of or repelled by technology per se. Okay, that's the context.
Since purchasing my Kindle, I have read 13 books in full, of which 2 were read on the Kindle: Charles Bukowki's Ham on Rye ($1.99 special) and George Pelecanos's What It Was (new book, 99 cents special). I have also read stories from several collections, including West Coast Crime Wave and Patti's Abbott's Monkey Justice. (I actually bought the Kindle so I could read WCCW, where a story of mine appears.)
I also started reading several novels -- and have left them unfinished at a much greater rate than I abandon print books. I also wouldn't say that I've abandoned these books -- I may dip back into them at any time, though with loss of continuity. I have also purchased many more ebooks than I am going to read. They don't take up space, and they are cheap; they are almost bought defensively so that I don't kick myself for not jumping on them when I had the chance. I've bought crime novels by McBain, Block, Disher, and others, usually for $1.99. I've downloaded a few books for free and never paid more than $2.99 or $3.99.
Generally, I continue to read from the printed page. That said, I read Ham on Rye and What It Was quickly on the Kindle, mostly at home, and stuck with them because they were particularly good books. I went on to read print editions (borrowed from a neighbor) of two other Bukowski titles. I guess the bar is higher for me to get through a book on Kindle.
Here is a counter-example of sorts. I recently read (in print, from the library) Paul Barrett's non-fiction book, Glock: The Rise of the American Handgun. This was a good book, but not a great book. I could see myself forgetting about it on the Kindle, but its insistent presence in my house (with a cover picture of a Glock) kept me at it. I haven't dipped into Kindle Singles or novellas -- but I like the idea of a shorter long format. Glock would probably be fine as a 30,000-word ebook -- longer than a long article but not puffed out to book length.
My Kindle has also been valuable for travel and short reading breaks while running errands. Recently, I stood in an hour line at Disneyland -- and I read McBain on the Kindle to pass the time. The Kindle is small and seems sturdy; I often carry it in a coat pocket without a Kindle cover.
So, that's my middle-of-the-road take on the Kindle as a reader. If I were a publisher or were opining in my semi-capacity as a commercial genre fiction writer, my take might be a bit different. If I were writing as a citizen-consumer concerned about competition-antitrust, I would certainly raise some red flags about Amazon (and probably Google). I don't like that I've aligned myself so closely with Amazon -- but I don't have strong allegiance to Big Six publishers either. My views and experiences are sure to evolve, and maybe I'll report back. Onward...