What others said + it depends on your location, different GPS satellites serve different continents (usually), so GPS might work better/worse in Europe compared to South Africa (as an example).
Wait, so with the new iphone I will be able to see my location on a map with this accuracy? So basically if a map resolves down to one foot I will have the location pinpointed to a foot from where I am? Currently it’s like 20 feet accuracy.