Hmm call me crazy but I prefer having an actual GPS data logger on my camera rather than a phone. Aside from the frailty of phones, the poor GPS performance in general, the very short battery life (especially while GPS is on and while applications are running), I wonder about how reliable a signal to a device that may be doing any number of things may be.
I suggest you look into a Bluetooth GPS unit available from pretty much any reputable dealer such as Holux, and a little bluetooth receiver for your camera. THey can usually also be linked with phones allowing you to use the phone without horrendously raping your battery.
And holy crap I just saw the price of that thing. You could get a dedicated good GPS unit for about half that price and it doesn't need a phone...