“The upgrade transports a flurry of added functionality to the instant messaging platform, including the ability to use Siri to place calls and compose messages, but you’ll need to be running iOS 10 to take full advantage of them.
Aside from Siri integration, Version 2.16.10 also pushes incoming calls to the lock screen. This means that you no longer have to frustratingly swipe right on a notification to open the application when someone’s trying to reach you. Instead, you can answer or decline WhatsApp Calls in the same way you’d deal with a regular phone call.” – The Next Web
That sounds extremely convenient, but let’s take a closer look. WhatsApp is fabled for its encryption (using Signal), strongly disliked by the secret services and governmental agencies because it’s extremely hard, nigh impossible to decrypt.
But convenience always comes at a price of security, in this case Apple would have all the data. Why? Because when you ask Siri something it’s like a Google search, the expressions the commands are stored on some server in Apple’s cloud. While as we could see, Apple is very protective in the case of user privacy, it does not mean that they cannot use that data themselves.
And in case of a data breach (and they DO happen, see: The Fappening(NSFW)) all your secrets become easily accessible in an instant as part of a huge database (even though the data is anonymized the “Siri send a message to Jack Smith “I love you” even as a string is very much usable).
Even though there is usually some encryption in place when your messages go through multiple service providers, the chance of them leaking out is increased tremendously. Simply saying: in the moment you speak to your Siri, Cortana, Alexa or other digital girlfriends you are giving up a huge amount of control over your secrets.