Note that the book is no longer $0.99, as stated in the article. It's currently $8.39 (vs $9.00 for the paperback). I always get disappointed to see such a small difference in price between Kindle and paperback.
Yeah, it throws me into a calculus of tradeoffs. Am I willing to bet 61 cents that this book will be good enough that I will want to lend it to a friend? What are the odds that the used bookstore will pay something for it? If I do decide to keep the physical copy, which book on my already-full shelves will get removed in favor of it?
Given that it costs them more than 61 cents to print and distribute the physical version, which I interpret them as gouging on the electronic version, there's also a fuck-me-no-fuck-you urge to buy the physical copy.
That's definitely progress. But what I really want is an ability to upgrade. I buy the Kindle version, and if it is awesome, they let me buy the print version for the difference (possibly plus a nominal amount like $0.99). Then I can defer the physical-or-virtual question until later.