The cocktails are searchable, favorite-able, and include bibliographic information on what book they came from in what year. You can also forward a recipe to a friend or Twitter what you're currently drinking.
The only thing it doesn't have is the ability to add new ones to your personal database. Cocktail 2.0?
I finally upgraded my old iPhone to have the App Store, so this was my first purchase. The best part about it is that it only costs ten bucks.