Ever since the announcement of the iPad, many seem to expect everyone to choose sides. If you want an iPad, you must not like your Kindle. If you have an iPad, you will not want a Kindle. If you have a Kindle, you will not want an iPad.
Hey, people, they are not the same type of device. Did Steve Jobs say it was an e-reader? No, he said you could read books on it—not the same thing, You can also watch movies and sports, get e-mail, play games and more. I am perishing for an iPad and have to wait till "late April," as Apple puts it, to get a 3G model, thus will not even be able to join the happy band of brothers and sisters on April 3rd in their delirious joy over the new toy.
On the other hand, I happily read on my Kindle and know that I will continue to do so long after I receive the iPad. To be without my Kindle for even one day would be sheer torture to me since, besides books, I read newspapers, magazines and blogs on it. One blog is the NY Times Latest News which is updated many times a day. I only care about the content and it doesn't matter that the pictures are in black and white. On the other hand, if it were National Geographic, with colored pictures, it would be best on the iPad—no contest. Technically I can read e-mail on my Kindle through the experimental web browser, but I don't, and do not know why any one would put themselves through the slow torture. E-mail is always with me on my phone and will be even better on the iPad.
Why do I love the Kindle for sustained reading? Because its e-ink screen is easy on my eyes and I literally read faster using it, possibly because it takes less time to click Next Page than it does to turn pages in a real book. Also, if the ambient light is a little dim, I can up the font size to make it easier. Backlit screens make my eyes burn after a short time, so I am unlikely to do much sustained reading on the iPad. Someone is bound to comment that a backlit screen does not bother HIS eyes. Well, good for him. I've been light sensitive all my life and it only gets worse.
The Kindle that I think is dead in the water when the iPad launches is the DX. It appears at this time that textbooks and college material in the form of pdfs will work much better on the iPad. The DX does not deal well with pdfs because it does not make them re-flowable. Since I can already re-flow a pdf on my iPhone, I know that it will be possible on the iPad.
To wrap up: my 6" Kindle and my iPad will co-exist just fine.