I have between 100 - 200 cookbooks on my shelf, and this app is more useful than all of them. For the casual user, it is a great way to keep and store recipes from the Internet or those few important ones you put in by hand. For those who want a bit more, it can easily organize your ENTIRE recipe library (and more importantly, it is very easy to re-organize - if you want good category suggestions, try the indices of your biggest print cook book).
Having your entire recipe collection at your finger tips is amazing. Not only is sharing recipes easier, but its so much easier to plan meals (instead of standing at the grocery store wondering what to buy, you just check the app and choose).
I bought it for my iPad, iPhone, and Mac book. So worth it.