On the face of it, this is true. Since most people enable iCloud backups of messages, which are not encrypted, you should basically think of iMessage as unencrypted, unless you are
very sure both you and the person you are messaging do not have iCloud backups enabled.
On the other hand, I'm not sure how much to trust Zuck's claims of WhatsApp encryption, or if external people have attempted to verify the claims, but it seems like such a big deal to lie about, that it's probably true?
Of course, that's only going to provide you passive protection from things like automated scanning of messages. If you become a target, it seems as though there are always exploits floating around which can be used to hack your phone, and then all bets off.
On the other hand, I'm not sure how much to trust Zuck's claims of WhatsApp encryption, or if external people have attempted to verify the claims, but it seems like such a big deal to lie about, that it's probably true?
Of course, that's only going to provide you passive protection from things like automated scanning of messages. If you become a target, it seems as though there are always exploits floating around which can be used to hack your phone, and then all bets off.