Have Galaxy Fit for about 40 days now. In general I love it. I will share some issues and feedback, I hope they get fixed with software update in future:
1) Sometimes at rest, the tracker shows double pulse. For example my pulse is 75 (double checked it using S9 and manually with a clock and finger). But the wrist reading show 150. Happens mostly when I am calm down, not doing any kind of exercise. This happened 3-4 times in the last month.
2) Sometimes after hitting DnD from the Galaxy Fit, it becomes unresponsive for about 10-20 seconds, and even the hardware button do nothing. Probably some sync issue, it fixes it if I check DnD from the smartphone. From the Gear app I have selected 2 way sync, but it seems to sync only cellphone to wrist and not in reverse.
3) I would love an option for the auto-tracking walking to record GPS, as it does if started manually.
4) If I go to sleep at 10PM and wake up at 11:50PM for a minute or so and then conitnue sleeping until 7AM, the tracker records this sleep for the next day, and shows 9 hours of sleep. However the Samsung Health App shows it wrongly as 7 hours of sleep, and 2 hour of nap for the previous day.
The health app is correct from date/time perspective, but tracker behaviour looks more logical. However the real issue is they show different things, and the inconsistency is bettering.
5) One time it reported a 1 hour sleep, while I was reading a book. This is not the issue itself, the issue is when I deleted the recorded data from the health app, it still shows in the clock, more over I don't have stress mesurment for this hour. I hope it gets better integrated with the provided software in the cellphone in future.