There have been many, many variety shows in the history of television. Many were very good, others were very bad. But most seemed to follow a similar format, offering music, comedy, sketches, and celebrity guests.
The Smothers Brothers Comedy Hour was no different in its format. What made the show stand out from all other variety shows were (1) the unique humor of and relationship between Tom and Dick and (2) their willingness to push the bounderies of what could and could not be said on television.
As for the second element, we aren't talking about dirty words; we're talking about saying things that were (gasp!) critical of our government and its dealings. The Smothers Brothers' show was the first to tackle the problems and controversies of the very troubled and changing times of the late 60s. They embraced the youth movement, the anti-war movement, the hippy culture, and the anti-establishment feelings of the time, and they allowed their show to be vessel for contrary and controversial opinions and attitudes.
At the same time, the show was very funny, smart and entertaining. The Smothers themselves always seemed to be on the mark with their hilarious routines and brotherly arguments interspercing their folk songs. They had an excellent cast of regulars (Pat Paulsen, Leigh French, Bob Einstein) and a wonderful mix of old-school and new-school celebrity guests.
So, while its format was familiar, the show itself was like no other on television. It was controversial and entertaining at the same time, and it paved the way for greater and greater freedom of speech on the small screen in the years to come. There will likely never be another show like The Smothers Brothers Comedy Hour.