After borrowing a Kindle on a flight and reading a couple chapters on it, it was the most craptastic experience I've had reading, tbh. It lookedand had the same ease of readabilityof a late 80's/early '90's display, and the navigation was, well, less than well-thought out. This is why is didn't care at all about the iPad's readeruntil I used it the first time.
I've been through four of five books now (two of them Stephen King novels!), and don't want to put it down. Regardless of ambient lighting, it's clean, clear, and a joy to read from, and turning pages is actually turning pages. Who'da thunk. Unlike the Kindle's method, which feels exactly like reading text on an LCD, the iPad's book reader is much more like a natural (or at least historically accepted) means of reading a book.
Personally, I don't think Amazon really ever cared about the Kindle; it's just a one-time purchase. It's really all about the books, or why else would the reader software be available on so many platforms? He with the better subscription model wins. 😉