I think people who regularly drink Coke might not notice the difference right away but for someone who drinks diet drinks, regular coke tastes like straight syrup now.
I noticed immediately. I find the flavor of artificial sweeteners (and some of the recent plant-derived sugar substitutes) as distinctive as you find sugar.
I recognize the irony of including HFCS among the "natural" sweeteners. Isn't that just 10,000 spoons (of sugar)?