It is a problem for me, probably about 3-4 on an annoying scale as your friend said. I often use my phone in bed with head half in pillow -- FaceID almost never recognizes my face in this position and I have to either move my head or use the passcode.

Even if I'm in a normal upright position, it has a higher error rate for me than TouchID, though it's mostly accurate and fast.

All that being said, the upgrade is totally worth it regardless. I went from a 7 to a 12mini, and it can just handle way more stuff and without delays/glitches.