Earlier quoted context omitted.
I don't know where I read it, but it always stuck to me: identification is more like a username, not a password, and should be used as such.
I believe everybody knows fingerprints or face are not a perfect solution for unlocking mobile phones, but so far they seem to be the best option currently available (taking into account the ease of shoulder surfing and inconvenience of entering secure passwords on small screen).
I'm willing to neglect the shoulder surfing attack vector as I feel I keep my phone sufficiently secure from pick pocketing and am not afraid of an "inside attack". Might definitely reconsider this, if I would have to carry a business phone with important secret information though.
[1] https://math.stackexchange.com/questions/634437/how-many-com...