I just pre-ordered too - the hardcover even though the kindle is cheaper.

I love the library, and mine is now open with various limiting restrictions. But for books like this I prefer owning a copy rather than reading from the library.

Ditto for kindle. I have a kindle and read on it all the time. But mainly for novels where I start at the beginning and read to the end. For books I read for reference, and which I might want to refer to sections more again, I still love a good hardcopy.