As long as you think face or fingerprint as an username and not as password, they are kinda fine.
You should be able to change your password, so there are not good. They are also public information.
For now, they work as they are still hard to fake, but that might change over time in the future.
I use finger print scanners at home because it's less keystrokes.
But not on my phone. Both because my (trusted) friends sometimes need to borrow a phone, and also for the very rare chance police detain me and try to break into my phone without a warrant.
Legally, you don't have to tell a cop your password, but they can physically force you to use your finger/face to unlock your phone.
