I'm amazed at the price for that iOS app. Are there such fans that would drop that kind of money for what tends to feel like a disposable purchase?
And it will be an odd thing though when you have a coffee table with an ipad instead of books... I think that's where Surface will come in handy.
I have bought $10-30 apps in the past (mostly for music production) and have been happy with all of them except one, which I returned for a refund.