I just got back from 12 days in Switzerland, Austria and Germany. I brought this app, the Ultralingua German Dictionary iPhone app, plus another paper phrase book.

For the cost of this application, I would not purchase it again. The "Categories" section of most common phrases option is about the same as the free applications. For the full listing of phrases "view all", the search utilities make this very difficult to use. There is no index to take you right to a word or phrase based on the letter of the alphabet and no scroll bar to adjust. You have to drag down through pages and pages to get to the alphabet letters you want. The search function does not find many words, and overall the number of words and phrases is just not worth $10. Save your money and look for a different app.

these are excellent guides. as other reviewers note, the search is key. awesome feature. i've yet to occupy a couple hours prepping during a flight, so i'm not sure how the battery will hold up, but so far, so good.