The primary benefit is for people who do a lot of distance-based athletics. I bought one recently because in addition to all the usual smart-phone/fitbit features, it works so well as a stand-alone athletic device. Now I can go running with just the watch for GPS+HR and a lightweight iPod shuffle clipped to my waistband for music. No more gigantic phone bouncing around in an armband. Plus the battery life is insanely good so you can easily track hours-long activities with plenty of juice to spare. It also can be used to track swimming and other water sports that you'd normally avoid using your phone for at all. I do some hunting, so I like that I can set a waypoint when I park and use the track-back feature in case I get turned around in the woods.