Next month I am replacing my phone and my car and one feature I have been on the fence about is GPS. What are you opinions of using the iPhone as a GPS? My alternatives would be mounting my iPad somehow and adding a GPS module, getting an in dash GPS (I was getting a double DIN radio anyway), or getting a dedicated GPS. I don't need GPS often enough to justify buying one, but I have been in very frustrating situations where I really wished I had one. What are your opinions?