Lou Schneider said:The GPS only works when you're in a data area - if there's no service the GPS becomes a brick. So don't expect the phone to bail you out while you're walking in the wilderness (unless you're on a mountaintop that sees a TMobile tower).
Ain't that the truth. I started to rely on my iphone for geocaching then got somewhere that there was no service and didn't have a GPSr with me. And using the GPS function will suck your batteries dry in a hurry. We use Map My Hike and North Face Trailhead when hiking but usually turn it off when we're not actively using it. It's fun to leave a footstep trail but sucks when the battery dies.
Wendy