I really don't care for it. I always use a PIN. I've tried using WH on numerous occasions but I wear reading glasses and its just too much of a hassle trying to get it to recognize me. Entering my PIN is much faster.
Not always needed to stare at Microsoft. Just improve recognition by starting at 4 or 5 different places. Mine now unlocks even when I am looking right in the middle of the screen e.g. OneDrive unlock.
Windows hello every time. I trained it a few times, and it works quickly every time. Only time I use a PIN is when the phone is on the desk and I can't be bothered picking it up.
I love Windows Hello. I have optimized the iris scan in many lighting conditions and angles and I can open it quite easily without it being even obvious. The optimization really does help big time. You have to run it in many scenarios, but once it's done it becomes perfect and super quick. Much quicker than if I put the pin in.
I said "it unlocks EVEN when I am looking at middle of the screen" - translation into English - it doesn't need you to stare at the camera. It works well if calibrated for different eyeball positions.