I think (again, my personal experience) that reading while also having a tactile sense of where I am in the book (say ~20% of the way through) makes it easier to remember smaller details; perhaps the physical book helps my brain create a sort of "memory castle" that a little progress bar on an ebook does not.
One example: I read all but the latest Game of Thrones books in paperback (well before the HBO show was even announced). I devoured them and was able to keep track of all the families/storylines without a problem or a second thought. I tried to read the latest one as an ebook and I found I'd have forgotten details of various storylines between reading sessions. I ultimately never finished it and I'm just watching the TV show now :|
Now when I want to read a book, I buy a book - I just can't get into ebooks. Sure, it's not as convenient, but it also doesn't need to be plugged in, ever.
Maybe it'll become feasible as the price for flexible eink displays drops.
Still, the Kindle is so damn convenient. It's just that it's not the same pleasurable reading experience for me. It's not true that the Kindle "disappears" like Amazon claims -- or maybe, it actually disappears too much!
There is something to be lost in digitizing our lives, automating our activities and putting it all online. Sure, we gain time to do other things, but it seems we then fritter it away scrolling through facebook feeds, tweets and whatnot.