https://signal.org/blog/whatsapp-complete/
I'm not sure if it's good enough to foil the US government agencies and their boundless stockpile of zero days. It did, however, make some judges here feel very impotent and powerless. They really, really wanted the messages in order to investigate some crime and couldn't understand why WhatsApp was resisting their requests. They ended up ordering ISPs to block the messaging service for a while as punishment.
https://www.forbes.com/sites/parmyolson/2016/05/03/whatsapp-...
Sure, it's true that people won't be able to audit the thing... But I think it's significant that a huge number of people are using end-to-end encryption by default without even realizing it. That's gotta count for something. It's a lot better security-wise than whatever it is we used before, and most certainly objectively a lot better than facebook messenger or SMS.