I use GPS on my LG Voyager. On Voyager and iPhone, the screen is big enough. The only downside is the volume of turn-by-turn directions on the Voyager is too low to be properly audible during driving. I have not used Iphone and I don't know how good the audio is on the iphone. I use bluetooth speaker so that I can hear the audio directions. As for the screen, I have no problem as the screen is as big as some of the Garmins.