It is not the heart sensor, the GPS, or the apps. The feature that actually keeps people wearing a smartwatch is almost never on the box.
The rated capacity on the box is a polite fiction. We measured what these batteries actually deliver, and the gap was bigger than expected.
No notifications, a battery measured in weeks, and one job it does perfectly. In an age of devices that want everything from you, that is radical.
I spent years rolling my eyes at the keyboard hobby. Then I lived with a good mechanical board for a month, and I get it now.