In contrast my Garmin and finger pulseox match exactly.
It does not inspire me to move up their range when this watch eventually dies: if they can't get the basic feature working, I have a hard time seeing how they're going to manage anything trickier.
That guy is a great reference, and through his videos you can find various measures where he compares devices against reference devices (e.g. the Polar H10 for heart rate for instance). A lot of the reliability of these devices relies upon a tight fit as well.
I really use the hell out of it. Yeah I can't play solitaire like an iWatch, but the battery lasts 7 days in the backcountry, the flashlight is unbelievably handy while hiking/camping/boondocking, and it helps me be healthy with all of the data. Being able to trigger my inReach is also a nice touch. It's definitely a tool rather than a fashion piece.