[glynjackson]

Instead of Facebook owing your photos and ID, they now own your phone numbers and your friends phone numbers! Not the best swap. WhatsApp Terms: "In order to prevent and reduce unsolicited spam messages, as well as to improve your in-app experience, WhatsApp uses the phone numbers from your phone's address book." "WhatsApp looks at the phone numbers in your address book, then checks to see which of those numbers are verified in WhatsApp." http://www.whatsapp.com/faq/en/general/20971813

[detaro]

So before they knew who he communicated with + pictures + other data, and now they know... who he communicates with. Given how easy most facebook identities are to connect to "real" identities, I don't see how them knowing the phone numbers is noticably worse.