So far, I'm liking my iPad for reading. No more attaching a book light to the PRS-505 that I previously owned or turning on the lamp and annoying my wife while I'm in bed. That in itself is part of the value of reading on the iPad.
Plus, I could flip over to Safari and type this reply as I'm doing now.
I have many computing devices including an Asus eeePC 1000HE netbook and a Macbook Pro and there is definitely a place for the iPad in my arsenal for casual reading, browsing the web and with access to several apps for a price that rivals the Kindle DX for the base model.