Like some of the PPs, we enjoy doing this once per trip. But we always have at least 2 Epcot days. I think your children are old enough to enjoy it, but make a pre show bathroom stop MANDATORY for the whole family. Once the ride starts, you can't leave until the end.
And its a bit more than a commercial for big oil, since they spend time exploring solar power, wind power, hydroelectric, and other forms of energy as sell.