I was very eager to see how the Strava app would perform on the Apple Watch, having now used the Strava platform to record my runs for the best part of 6 months. I decided to perform 2 test runs of 3.5km, one with the Garmin fenix 3 and the other with the Strava app running on the Apple Watch, and compare these experiences. The main point to note is that the Apple Watch currently acts as an extension of the iPhone, and uses the 4G signal and GPS from the Strava app on the phone itself, and relays that information to the Apple Watch. Quite simply, the watch acts purely as a second screen when you are running.
I will compare a few of the main running parameters between the fenix 3 and Apple Watch.