Mine works fine without an external antenna also. I think the main draw for me over the smart phone, was the battery life, and toughness. When I go on hikes, I stick in an external pocket and leave it on all day tracking, and its super easy to mark POI. I dont have to worry about it when the sand kicks up, it starts raining, or get bumped on rocks. It is a pain to put detailed names, but that can be done later. I do carry my smart phone also, each has its place, but the phone definitely wont track very long on the battery. The phone will geo-tag pics too.
Gary
96 FZJ80
93 W250 Cummins