“Full day, 18 hours” battery life ruined it all for me. Too much trouble to charge so often.
At least for me it is. And thus I get around 2 days battery life with a 4 year old series 2 watch.
Their official test includes "45 minutes of app use, and a 60-minute workout with music playback from Apple Watch via Bluetooth"[0] - so unless you plan on doing that you can easily expect double the battery time.
It doesn’t take long to get a reasonable charge on it. I usually keep it around 80% at most anyway. It gets me through the day at 80% and through the night since I use it for sleep tracking and alarm.
My colleague gets 24 hours battery life on her series 6. Still uncomfortable compared to the usual week+ battery life Garmins.
On the cheaper side, another colleague has an Amazfit Blip Lite which lasts 30 days on a 2 hour charge and can withstand up to 30 meters underwater.
I think the difference is the Series 6 screen never fully turns off. I imagine disabling "always on" mode would likely push battery life much higher, but that's just a guess