I'm not in the US, and I stopped using WhatsApp for several reasons. It doesn't provide me any benefits over SMS (people still need to know your phone number, for example, and if they change phone numbers, there's the whole game of figuring out who is messaging you). Not that many people I communicate with regularly really cared if we used it or another communications method either. It is one more app draining my phone's battery. And I want to limit the apps that Facebook can use to gain information about me.