I have previously used gps watches, but now I sold mine and use Apple Watch for running - even without my iPhone. I live in a city and often run between buildings. That means bad gps signal, and my calibrated Apple Watch is not much different from a gps watch that uses cadence/acceleration to calculate distance/speed when no signal. I found that Apple Watch is good enough for me. Especially with the built in heart rate monitor. Built in gps would be nice to have, but as most people, I know the length of most of my runs. Calibration seems accurate and that will be fine until a gps Apple Watch arrives. What about you?