The power and attraction of absinthe lie in its inherent contradictions. Though fortified with a formidable measure of alcohol, a depressant, it is also infused with powerful herbal stimulants, creating a psychic tug of war in the mind of the imbiber. Alcohol relaxes inhibitions and invites in new ideas, and the stimulants allow you to logically process the new data.
Foremost of the stimulants is thujone, the psychoactive chemical at the heart of the herb wormwood, which, along with anisette, gives absinthe its bitter, black liquorish taste. While once thought to instigate similar reactions as marijuana's THC, recent research suggests it modulates the neurotransmitter GABAA, which plays a vital role in cognitive thought. Subsequently, absinthe provides a level of clarity not usually associated with alcoholic drinks, and what artist worth his beret could pass that up?
The recipes for absinthe, and thus the flavor, vary greatly from manufacturer to manufacturer, as was true at the turn of the century when there were over 200 absinthe producers. Today, there are not nearly so many, but more and more crop up every day! That said, a few of the modern Spanish brands seem to have the best hold on flavor. At its best, and in varying degrees with brands such as Deva, Lasala & Mari Mayans, you will find a strong anise (close to licorice) flavor with undertones of its many herbal constituents.
Despite popular opinions, due mostly to people's erroneous assumptions upon sampling home brews, absinthe, when properly distilled, is not extremely bitter. Wormwood, whose extract used to be a popular ingredient in many perfumes, actually has strong floral & herbal flavor (and scent) that is heightened when extracted by proper distillation, which leaves behind many of the bitter absinthins. So yes, there is bitterness (probably more evident in absinthes with higher thujone content allowed), but it is an undertone, and not overpowering in the slightest. Absinthe King of Spirits Gold is somewhat more bitter than regular absinthe, yet paradoxically more smooth - the usual sharp 140 proof edge appears to be in hiding in the herbs.