I am so late on this thread!! I got an iphone 1.5 months ago and it is the best phone I've ever had.
The GPS is wonderful, I use VZ Navigator which I feel is the best spoken GPS app, any address that is saved in your phone autofills and you are on your way in a few seconds. Google maps app is really nice for public transportation, especially in NYC it shows the nearest subway and bus options.
Other stuff I use a lot is the iPod (music), Calendar, Firefox Home (save bookmarks at home and it syncs the bookmarks to your iphone), Facebook, Citibank, shipping trackers (USPS, UPS, Fedex), eBay, Etsy,
The best thing about iphone is that every app is on iOS, when I had other phones I used to get upset because this-or-that-app was not available for my phone.