Hello Apple Watch enthusiasts! For the past month, I was extremely happy with the AW Fitness Capabilities. As recommended, I took my iPhone for the first few runs with me, and after a while I left it at home. To run without my iPhone was one of the many reasons I bought the AW.- And running without it worked great, until I noticed, that the AW without GPS has no clue how fast you're moving. Small info: 20 yrs old, I run between 5km (3.1mi) in half an hour to 10km(6.2mi) in an hour a few times a week. My speed is consistently 10km/h (6.2mph) at 160bpm. I am accustomed to this pace and I can keep it. My AW showed me the same stats, until I took a run with my girlfriend... She runs 8km/h (4.9mph) pretty consistently too and I ran beside her. I checked my AW regularly and couldn't believe it. - It showed me the same exact stats as if I were running alone. After half an hour, my AW informed me that I ran 5km, when in reality, it was somewhere between 3.6 to 4 km. This was even move saddening, because my Heartrate was consistently at 140 bpm. Does the watch really think that all of a sudden I run the same pace with a significantly lower heartrate? My gf with runtastic and the right stats hid a few laughs, this run was very frustrating. I took a few more tests and came to the conclusion that the Watch basically remembers my runs with the iPhone and simulates these exact same runs when I leave the iPhone at home. IMO this is bs to say it nicely. I'm pretty much an Apple "Fanboy" and I believed them when they said "the Watch learns the distance after a few runs" but this time, at least in my case, this is far from the truth. I love my watch, but this is a dissappointment. Honestly, I wouldn't expect a watch without GPS to register my runs correctly, but Apples marketing told me otherwise, and imo simply lied. I encourage everyone who often runs with the watch alone to take a chilled run and compare your results. Hopefully, the AW 2 will have GPS built in. Greetings, Flori TL;DR- AW has no idea about your distance and pace (even after calibrating with your iPhone) and simulates the stats from past runs with iPhone. At least in my case.