Ever since the Face Unlock feature was first implemented in Ice Cream Sandwich, it has worked pretty much the same way: You train your phone to recognize your face, and when your phone is locked, the camera will fire up and try to recognize you. You’ll see yourself on the screen when this happens, and if the phone can’t recognize you in a few seconds, you’ll be asked for your backup password, PIN, or pattern.
In Android Lollipop, it works completely differently.
Face Unlock now lives in the Smart Lock menu in your security settings, so you’ll need a PIN, password, or pattern lock on your device before even attempting to set it up.
Once you get to that part, the set up is still relatively familiar: You train your phone to recognize your face, by adding your face as a “trusted face” in the Smart Lock menu.
Finally, when your phone is locked, instead of showing you what the front-facing camera sees when trying to recognize you, you will simply see a person icon at the bottom of your phone. If you are recognized, it will turn into an unlocked padlock – simply swipe up to start using your phone. If you’re not recognized, it will turn into a locked padlock, and you’ll have to swipe up to enter your password, PIN, or pattern.
Unfortunately, for long time Android users, this isn’t the most intuitive set up for Face Unlock. I kept expecting to see the front facing camera viewfinder, like in previous versions of Android, but when I didn’t I assumed I had found a bug. It took a lot of playing around with this before I figured it out, so if I save you a few minutes, my job here is done!