SP4 user here too, Windows Hello failed exactly once for me: when I was setting it up. Ever since then it's worked flawlessly. It's so insanely good it's almost hard to believe Microsoft built it.

When Android first came up with face recognition it was a gimmick; half of the time it didn't work, it took too long, you needed the right amount of light, etc etc. But I can confidently say that Microsoft's implementation is nothing like it, they've actually made it work.