It was only a matter of time before someone tried to crack Face ID, and now one Vietnamese company is claiming it can be done...albeit with a lot of effort, and definitely not by most average users (unless you have a super identical twin).
UPDATE 15/11/2017: A recently released video shows a woman demonstrating how her iPhone X was unlocked by her 10-year-old. How is this possible? Apple does note in a security paper that children under the age of 13 with "undeveloped features" could cause issues with Face ID. In other words, if your kid is basically the spitting image of you when you were a child, the iPhone X is likely be fooled. Interestingly, it's noted in the video that the child managed to fool the mother's iPhone X multiple times, but the father's only once.
Not actually easy
Meanwhile, the Vietnamese firm that claimed it had cracked Face ID, Bkav, said they managed it by creating a composite 3D-printed mask assembled from plastic, silicone, paper and some makeup, all of which apparently cost just US$150 (RM630). There's a chance though, that in its testing, the company 'trained' the iPhone to recognise the face used.
Should iPhone X users be worried? Not necessarily - to get the requisite material you would need a detailed scan of someone's face and not just a flat photo. Like, you can't just take a photo of someone in the crowd and use it. You'd need a detailed, near-exact digital scan.
What is intriguing, however, is that Bkav's model used 2D, non-moving representations for the eyes, which means that Face ID's sensors don't register eye movement. The magazine Wired also found that the sensors only check a portion of a user's features.
Ultimately though, it would take a lot of effort, time and some money to hack into your phone and unless you keep incredibly valuable data on it (perhaps don't?), the average person has nothing to worry about.