It was fun! The reaction bubbles out CO2 which collects on the shell. The bubbles at the bottom gently roll the egg. That’s handy since you don’t have to keep coming in to rotate the egg or stir, and it’s fun to watch. We left the egg to toss and turn all night.
The next morning we rushed down to see what had happened. The egg now had only two receding polar caps of calcium carbonate, presumably because the rolling action affected those ends the least. A quick rinse and our vinegar egg was 100% shell free.
I was surprised at how delightful the shell-less egg is. So natural and familiar, but so unlike an egg.