I have a bottle of it and enjoy it from time to time. The 'pouring the water' over the sugar cube method is the 'original' and 'correct' method, if you will. The 'Czech fire ritual' is a newer way of doing things -- pure Hollywood.
As with anything, there is a difference in quality between various brands. Some of the higher quality brands are modeled after the swiss 'La Bleue' -- they are clear with a faint louche (cloudiness when water added). They cannot legally be imported, but possessing absinthe is not illegal here. Kind of like cuban cigars.
The wormwood content is much lower now than in the past, but the drink does have a mild 'buzz' which is distinct from that induced by the alcohol content.
Absinthe was hugely popular in Europe in the last century, and even threatened the French wine industry. The drink was later outlawed in much of Europe and in America due to some highly publicized murders and other events, which were linked in the publics mind to the Absinthe -- much as alcohol was linked to a myriad of sins in the temperance movement. It is probably true that some absinthe caused human illness, but the wormwood is not thought to have been the problem -- rather, heavy metals from poor distillation techniques. Some of the 'nagative' imagery comes from Van Gough, with the amusing 'ear' incident related to absinthe. But consider that he also drank paint and paint thinner.
Betina Wittels has a good book on it, and also sources 'the green fairy' in the USA. Much more info here
http://www.feeverte.net/