But I'm not planning to do any reading on it. I will keep reading on the Kindle, for one reason that I'd not expected: Weight.
The iPad feels super solid and sturdy, the Kindle seems plastic and flimsy by comparison. (The Kindle may feel flimsy, but it is tough--both mine and the wife's have easily survived numerous drops onto the floor.) Because of all the solidity, the iPad feels heavy--much more so than I expected. It's nearly a pound more than the Kindle, and when sitting in bed reading every night, that will be a huge difference. Where the kindle starts to slip out of one hand as I'm dozing off--the iPad would fall.
After just the first day (doing lots of programming on iPad apps) the Kindle felt like nothing when I picked it up before bed. I may buy books via the Amazon website on the iPad, then read on the Kindle.
If you read a lot where the book is held in your hand, you want a Kindle for reading over an iPad. But for everything else, you want an iPad.