First things first: I don’t use WhatsApp. I’ve used it a long time ago, before they had decided to take money from their users. Even though it was just some cents, I was and I am not willing to pay for a company which is not willing to speak with its customers, to inform them about future technical plans or recent problems, especially concerning data security. And after being bought by facebook, WhatsApp got even less interesting to me. But that are personal feelings and decisions and not universal. But of course I do use some instant messaging systems, especially Google’s Hangouts.