The last time we got it, we kept track of our receipts for about two days to see if we were spending the value of the CS plan or not, and gave up after lunchtime on the second day, because we were so clearly ahead. Now, it was a slightly better value at the time because it still had two snacks and you got two drinks at breakfast, and we did have a very specific strategy that we followed, which at many meals involved splitting large meals and getting a separate dessert with a snack credit.
I wouldn't pay for the desserts much of the time if they were OOP, but that didn't mean that they weren't happily eaten. We ordered what we wanted, but I don't think it was ever the cheapest thing on the menu. And we're very fond of the Wolfgang Puck Express. They may have changed it, but they had a $17 salmon entree that was very good.
If you are a vegetarian, or a very light eater, or don't drink soda/eat desserts, it may not work that well, but it's really not hard to spend the value of the plan. It isn't a massive savings, but every little bit helps, and it lets you eat what you want without guilt or hesitation.
Based on the menus at All Ears, if you were at Epcot--
lunch at Sunshine Seasons--Steak and Blue Cheese Sandwich 9.49
Cupcake--4.39
Large Fountain drink-2.99--
16.87
plus 6.5 percent sales tax--17.96
then for a snack--
ice cream crepe at Chefs de France--4.93
plus 6.5 percent sales tax--5.25
and for dinner--
Boulangerie Patisserie Les Halles--Poulet au Pistou--9.00
Framboise-$5.50
Limoade-$5.10
19.60 plus 6.5 percent sales tax--20.87
We're at 44.08 plus the value of the resort mug. Not a huge savings, but with the exception of the fancy French soda, not the most expensive thing in the park either. As long as you want and will eat it, the QS represents a reasonable value.