I briefly toyed with the idea of getting an iPad. I may yet get one, though not until the next generation comes, out, one with working USB and a camera. But all I had to do was hold it in my hand to know it wouldn't replace the Kindle as a book reader. The iPad may be superior in every other way, but the weight alone is a deal killer. I returned the Kindle DX because it was too heavy to hold comfortably in one hand while reading. The Kindle is heavier and even more awkward than the DX.
I also, prefer the non-back lit screen as I find it easier on the eyes. And, even with the iPad's extensive battery life, the Kindle still wins that fight as well. Magazines, web reading and all other reading is, unsurprisingly, better on the iPad. But, when it comes to reading books I find the Kindle to be the superior device. Book reading is a relatively specialized activity; one in which I neither want, nor appreciate, having endless other options available and intruding (probably one reason why I don't read so many books these days).