The system (Smile to Pay) is purportedly resistant to spoofing with photos and other tricks. It relies on both depth-sensing cameras and a "likeness detection algorithm" to make sure it's really you. Reportedly, the technology is good enough that it can accurately identify people even when they're disguising themselves through makeup or wigs. You shouldn't have to worry about someone buying lunch on your dime just because they look vaguely similar, in other words.

It won't be surprising if this payment system spreads in China, but don't expect to see it gain much ground elsewhere. Countries like the US have stricter rules on biometric data, and there's frequently greater stigmas around handing face data to someone else. Not everyone feels comfortable handing face data to a payment giant, even if they know the data should be kept secure. Still, this could represent the future of fast payment (or a commonplace option) in some parts of the world.