My iPad(1) is my e-reader.
I have iBooks, Kindle, and Overdrive by Adobe apps on it, so I can borrow books from our local library in whatever form they reside there. I can, of course, also buy e-books from iTunes.
I very much like the ease of any of these apps, although, I do fine the Kindle app a good bit less than user friendly, as you need to go to the Amazon site and "manage your Kindle" in order to return a book to the library before it 'expires'. I think that many others find this the same as books are 'very slow' to be returned and I assume that folks are just letting the app return the book after 21 days rather than mess around with the other hassle (just my opinion).
I do very much like the iPad form factor, the ease of reading on it, and being able to have music piped to my hearing aids via bluetooth while I read.
Bob K. rnkiii