That's true with iCloud Backup specifically, not iCloud. But unsecured notes and photos don't fall under the encryption umbrella, so syncing those means you lose privacy. Even syncing messages is safe, since messages are shared with your private encryption key. iCloud Backup and photo syncing are pretty much the bones thrown to US law enforcement.
> Even syncing messages is safe, since messages are shared with your private encryption key.
Do you mean the syncing of messages between logged in devices via the normal iMessage delivery mechanism (which I know is encrypted), or the "Messages in iCloud" feature?