I have one. The one in the picture. And I like it, for all the obvious reasons. I'm carrying about 300 books around in my back pocket, but a couple of curious things ...
1. I start many more books than I finish on the ereader. In fact, in about 6 months of ownership, I've only managed to finish one. The temptation of holding a whole library in your hand, accessible without even having to get up out of your chair, is too great a temptation for the over-active mind (never confuse an over-active mind with an intelligent one).
Then, without being able to hold what is gone in the left hand and what is too come in the right, it is possible to feel a little lost in an electronic book, to loose your sense of progression through the pages as well as the plot, and perhaps this causes me to give up on books I otherwise wouldn't. I know I have more success on the ereader with books I have already read many times, where the words themselves remind me of where I am in relation to the front and book covers of the now incorporeal book, than with books that I've taken up for the first time.
2. I remember comparatively little of what I read on an ereader. Not only do I forget the details, but plot twists and minor characters. Perhaps the smell of the page, the feel of it, its colour and texture, the sense of its weight in our hands, are all triggers for memory, or even essential to it. I know sometimes I will look for a sentence in a printed book, and have a very clear notion of whether it was in the upper middle or lower part of the page, or whether that page was on the left or right, without ever having made a note of it at the time of reading.
Pensees - spelling and punctuation mistakes and all ... I believe at least three quarters of what I say. ... And the good stuff only stays posted for an hour or two.