I have a nook tablet, and I've enjoyed it. I do a lot of reading on it, and use it to review chapter drafts of my novel, as seeing them in "book" format makes it easier to see with fresh eyes. I still read a fair number of books on paper too, but the reader is handy to take to the gym. Not interested in reading books on my android phone, as the screen is too freaking small to read at a comfortable sized font and not have to turn the pages ever two sentences. It's very nice to be able to slip it into my briefcase to read during down times at work, or to take to the gym (sits up on the ledges on the exercise machines much better than paper books do).
I have a kindle app on my computer, and I've got a couple kindle e-books on that, though they're reference books.
Lately, I've had the frustration of some new books I want to read coming out and not being available on nook, though. One became available after a month or so, but another probably won't for quite a while, as the e-contract for this book was published via an imprint that has been bought by Amazon. They're DRM locked, so you can't use calibre to convert the kindle format to nook (epub), which is irritating.
One general disappointment with ereaders is how a lot of older titles from some of my favorite authors have not been brought out in digital format, even though they've been reissued on paper. I have a ton of mouldering old SF and F paperbacks from the 70s and 80s on my shelves, and I thought a great thing about ebooks would be I could replace those books as ebooks. It surprises me that they haven't, since it seems bringing out a new printing as an ebook would be cheaper and easier than the paper runs of these "collector's" or "gold" editions of these books.