A bit more info from Apple:
"yes it is true that the iphone has a dedicated gps recevier and it is also true that some navigation apps like the standard maps app and the garmin navigator need some kind of connection to fetch the map ..
but the gps recevier is a AGPS receiver, this means it has a standard gps receiver but it also uses the cell towers to assist the gps lock and to speed up the locking process. without some kind of conenction to the tower or a wifi connection, a full gps lock can realistically can take 15 or 20 minutes to get, if you do not know where the satellties are. the gps satellites only broadcast once every like 30 seconds? and with 30 of them it means it can take 15 mintues to get them all
the iphone uses the towers and wifi connection to download information on where the satellites are and then looks for them to speed up the gps locking."
So it would appear that if you have enough time the phone will possibly make a gps lock, but it will not be as fast as a traditional GPS. Obviously if you have a data connection of 4G or higher, the GPS should work quickly, but if no cell service is available, then it may take a bit longer.
I guess the GPS is what the star finder apps also use to locate your position under the stars, and I have had times where my apps will hit immediately and other times, can't get a lock on the constellations. So some of the same thing must be going on.
Paul C