On iOS, if you swipe to go back but let go BEFORE you have reached the mid way point (half way across the device screen), the app displays the back view, however it is completely unresponsive.
However, you can then perform the swipe-to-go-back gesture again and the page that was in view appears again and you can continue swiping back.
It is not until you do the full gesture or release AFTER the mid way point that the backwards navigation actually works.
Created an issue for this @ https://github.com/driftyco/ionic/issues/7093