"Ambitious health sensors declare war on a battery the spec sheet conveniently ignores."
The watch analyzes pulse data to infer patterns potentially related to sleep apnea and chronic high blood pressure. These are alerts, not diagnostic measurements, designed to tell you when it may be time to consult a doctor.
This is for the iPhone user who prioritizes cutting-edge health data and for whom an early warning of hypertension or sleep apnea is worth the premium price. The commitment to daily charging must be absolute.
Android users have no path to using this watch. Anyone needing multi-day battery life for ultramarathons, camping, or simple convenience should look elsewhere. Buyers seeking pure fitness tracking can get most of the core functionality for significantly less money.