Fitbit also says GPS tracking is more accurate on the Ionic, and in my experience
hiking and running familiar
routes, the
distances were in line with what I expected to see (a different experience from my testing of the Fitbit Charge 2 last year).
Crucially, with the Series 3, there's built - in GPS, which can measure
routes, pace and
distance when you're out on a run or
hike without needing an iPhone — often a criticism of the first Apple Watch.