I mostly use it for connectivity - checking messages and notifications. I haven't done any exhaustive testing, but what I use seems to usually be okay. Heart rate, steps, sleeping stages...those seem to be pretty decent. I'm not sure how it decides Light/Deep,REM sleep stages, but it seems to accurately note when I wake up to pee in the middle of the night, and I assume the brief spikes into wakefulness are just me getting restless. Blood/Ox levels get wonky; I question their accuracy. Sometimes during overnight monitoring they drop out completely for periods of time.
