There remains a large gray area and many pending court cases regarding search and seizure of smartphones by the police and federal agents. Currently you can not be compelled to unlock your smartphone and police need probable cause to seize it, but border agents do not. With Face ID however, it wouldn't be difficult for a federal agent to take your iPhone and point it at you in order to unlock it. Considering how much personal information people have on their smartphones, the heated debate between privacy advocates and law enforcement is not surprising.
While you could have many users with Touch ID, Face ID only works with one face, so each iPhone X can only have one user that can access it via Face ID. Of course you can always give your passcode to somebody to use once they've failed the Face ID authentication.
The iPhone X introduces some major design changes including, most notably, the absence of a physical Home button. While this can understandably take some time getting used to from an ergonomic perspective, the lack of a Home button also means no more Touch ID, which was an incredibly convenient security feature not just for unlocking your iPhone, but for accessing apps with sensitive data as well. For this reason and for even stronger security, Apple introduced a new biometric scan with the iPhone X - Face ID.
— Mia Harrison (@ManxomeMia) November 4, 2017
Now that the iPhone X has been released, owners of the device are flexing all of its capabilities. One of the highlights is Apple's Animoji, which uses the front facing TrueDepth camera to animate wacky creatures. And what better way to use a $1,000 smartphone than to lip sync videos with those creatures? Enter the Animoji karaoke phenomenon, spreading across Twitter and other social media.
With iPhone X pre-orders still weeks away, Face ID has yet to arrive in consumers' hands. This hasn't stopped renowned KGI analyst Ming-Chi Kuo from predicting Apple's next moves surrounding the technology. Despite the fact that Touch ID was only introduced four years ago, Kuo expects Apple to leave Touch ID in the dust starting in fall 2018.