5G is entering uncharted territory. 3rd Generation Partnership Project (3GPP) Release 16 enables entirely new applications, expanding commercial mobile communications from familiar mobile broadband to the vast internet of things (IoT). 5G engineers stand before their greatest challenge yet: achieving the International Mobile Telecommunications 2020 (IMT-2020) vision for 10¯⁵ reliability and 1 ms end-to-end latency. Will it be an engineering marriage made in hell or heaven? Part of the answer, like in marriage, is to find out what you are getting into.