This is a great activity for the whole family. You see things in the countries you might have overlooked otherwise. Plus you will learn secrets in these countries! My little ones enjoyed having control of the cell phone!
My only advice is that if the park is busy, do not wait until you are ready to do the mission to register. When we were ready, we went to the kiosk and got a ticket (like a fastpass) with a return time of an hour and 20 mins. later to pick up our kimmunicator in the WS. By that time we only had time to do one mission before our ADR.