Many people cannot stand the sour taste of stevia, but I would prefer the stevia to Xylitol.
The bitterness of stevia comes from an alkaloid in the stem, not the leaf. Higher quality stevia made with almost pure leaf does not have that overly bitter taste. And the powdered extracts with 90-99% stevioside also have no bitter aftertaste.
But these higher grades only require tiny amounts for use. Generally a 1/4 teaspoon will replace a cup of sugar. But this makes it hard to spread such a small amount over something like cereal, and it will not hold moisture like sugar. So additives are often combined with stevia extracts such as maltodextrin, FOS, lactose or erythritol as flow agents and in some cases to help retain moisture.