In spite of what others have stated as fact, there is diversity in opinion on what constitutes an e reader.
MobileRead Wiki - LCD E-Book Reader Matrix
Wiki contains a list of LCD based e-book readers and some believe that the LCD based readers are superior.
One of the beauties of the IPAD design, in my humble and obvousy elderly and illconcieved opinion is that it can be an e-reader to some owners who buy it specifically to be a reader.
Personally I found that what I thought would be dissadvantages of the IPAD over my Kindle were not. True it is heavier and a bit more challenging to hold single handed while in bed, but you can not read the Kindle in the dark. And you can switch the IPAD kindle reader to white text on a black background for reading after the lights are out and the wife would complain if you had the lights on. I use it nightly in this manner and really enjoy it.
Again, at the risk of being called stupid and an Apple hater, I have to give kudos to the IPAD designers for doing such a good job at creating a device that while it does not displace my desktops or laptops, fills a niche that I did not know I had till I began enjoying using my IPAD.
And when I have it in reader mode, yes it is an e-reader.
I am leaping to a personal assumption that some are concerned that if they admit that it is a very good e-reader then that will somehow weaken their argument that the IPAD is a real computer. Interesting. Illogical and in my worthless and ill formed opinion wrong but interesting nonetheless