One other twist to this...
Altitude. Starting with the iPhone 6/6+ and with the Air2, an internal barometer is included as part of the hardware. SOME Android devices have a barometer. This can be important with advanced follow modes like Litchi Magic Leash and Autopilot Airspace. If the app supports it, the barometer provides altitude information for the followed device. If that device runs up a hill, the drone will climb accordingly. With no altitude information from the followed device, the drone could potentially fly right into the hill in the same scenario.
Altitude. Starting with the iPhone 6/6+ and with the Air2, an internal barometer is included as part of the hardware. SOME Android devices have a barometer. This can be important with advanced follow modes like Litchi Magic Leash and Autopilot Airspace. If the app supports it, the barometer provides altitude information for the followed device. If that device runs up a hill, the drone will climb accordingly. With no altitude information from the followed device, the drone could potentially fly right into the hill in the same scenario.