not necessarily THE highlight, but i haven't heard anyone talk about how much more efficient the dodo code system is. it's going to make visiting towns so much easier than having to add people's friend codes, delete friends when you reach the maximum amount, wait for people to open their gates, know their town name, etc etc
1. The terraforming feature
2. Being able to go on random island tours
3. Being able to place villagers? tents and buildings, Future house plots. I think you can also except or deny permission for specific villagers to move in, but I?m not too sure about that.