THe reason that gatorade is good after a workout, or sporting event is because it replenishes the electrolights and other missing chemicals/things you lose/lower during exercise, it doesn't completely rehydrate you, that is why people mix gatorade and water.
Water is superior in everything else except sports... and even then, gatorade + water mix is far superior than gatorade alone.
EDIT: To clarify, I'm not saying Gatorade is bad, I'm just saying water is far superior than it in a large majority of cases. And in the cases it isn't, the mixture of Gatorade and water is far superior than just gatorade alone.