I can't speak for the Apple Watch, but the O2/BPM readings on some other watches are often dropped/delayed with the operating system taking priority. I was tryi

I can't speak for the Apple Watch, but the O2/BPM readings on some other watches are often dropped/delayed with the operating system taking priority. I was trying to use the heart rate data for a pet project and found its practically useless, on Samsung's watches its just enough data to show a few fancy numbers and thats about it. On the contrary, the Apple Watch ECG is quite accurate, not quite enough to replace the system the doctor makes me wear, but enough that apple can get a general idea of any defects and tell you to go to the doctor. The "regular" hear rate sensor isn't anywhere near good enough to be taken seriously, but its leaps ahead my previous samsung. I dream of the day where my Apple Watch can replace the myriad of annoying wires and sensors I have to wear to monitor myself. Even then, the Apple Watch has greatly helped me out when I've fallen and need assistance, and I've gifted several to my family just in case.