The effect of Bitters in a beverage is to balance, round and complex the flavor. The mouth has taste receptors for sour, sweet and salty, as well as bitter. The more receptors that are activated when a drink tickles on the way down, the more interesting the drink will be. Bitters are known to have been used correctly when the person enjoying the drink says, "Wow, there's something in the bottom of that drink." Consider it a resounding success.