If look at a villager who is sick before and after healing him/her with another villager, you'll see that not only will they be "cured" but their health points will go up a notch.

When the GC throws a party and cures the villagers, it doesn't change, and if it was too low, they still can die before the villager "dinner" raises the notch.

IMHO, when the GC throws a party, there should also be a visible "dip" in the food supply as everyone eats and drinks...

There are events that will cause their health points to drop, as well as just random sickness, old age or starvation. But mostly, when I've had a completed game, that is not something I've had to worry about.

But some other things I like about the GC:

1. He restores the berry bush and crops (to give the farmers something to do besides fish or watering the crops.)
2. He'll pick mushrooms if told to (due to baby booms, I've had some villages without any other kids!)
3. I like the bubbles and rainbows.
4. He frees his mother from two years of nursing!
5. He likes to dance.