With the latest update, iPhone users no longer have to wait for network signal to send messages. With WhatsApp (2.17.1), messages will be placed in a queue and sent automatically as soon as signal is detected, thereby allowing users send messages while offline.
This update also comes with the ability to send up to 30 videos and/or photos at once. Previous limit being 10. This feature has been available on Android for a while now and comes pretty hand when and/or where the network connectivity is poor. To have access to these, update your app via the store to the latest version.