Finally, which was feared has happened now. When the popular cross-platform messaging App, WhatsApp was bought by Facebook in 2014, it was assumed that the very premise of privacy on which the App was built, would be shattered. WhatsApp had gained trust and popularity based on its no ads policy and respect for users privacy. Naturally, Facebook buying WhatsApp had users worried that their data would somehow be shared with the social networking behemoth.
"But what WhatsApp users feared is happening now and Koum may have to eat his own words. WhatsApp has finally fallen to the lure of money and is loosening some of its own restrictions, and has announced it will begin sharing a limited amount of user data — including individuals' phone numbers — with parent company Facebook.
Officially, WhatsApp says that sharing this information means Facebook can offer better friend suggestions by mapping users' social connections across the two services, and deliver more relevant ads on the social network. Additional analytics data from WhatsApp will also be shared to track usage metrics and fight spam.
This, however, opens golden gates for other cross-platform messaging Apps like Hike if they can assure users that their data won't be misused like what WhatsApp will be doing now on.
I personally don't think that it will be a problem if whatsapp shared with facebook.. because the message are encrypted.