WhatsApp has provided more details about the new feature on aFAQ page.
Messages you successfully delete for everyone will be replaced withThis message was deletedin your recipients chats (*).
Also, your recipient may see your message before its deleted or if deletion was not successful.
You will not be notified if the delete for everyone was unsuccessful.
Additionally, this feature doesnt work in case of broadcast messages.
source: www.techworm.net
