Don’t count on that encryption. It’s a great marketing point that has no real way to verify or audit. And even assuming Whatsapp's end-to-end encryption works as advertised: that doesn’t mean that the app is free from backdoors.
Message contents also aren't the only kind of data that Whatapp knows about. Facebook doesn't need message contents to monetize your communications. They almost certainly harvest Whatapp's metadata and tie it to everything else they know about you.
If you like the service, that's great. Use it and enjoy. But don't assume that your communications are secure.
Whether I like it or not, I have to use it because it's what everyone here uses. There is no point in having a perfect fully audited free software messenger if nobody uses it. I'm just glad that everyone is using something this secure by default. At this point I'm just counting my blessings.
WhatsApp encryption is strong enough to defeat criminal investigations in my country. That has to count for something. They got so angry about it they blocked WhatsApp services for days and jailed Facebook people.
