The show centers on the relationship between an unconventional, 1960s-holder teacher (Mr. Moore, played by Howard Hesseman) and a special class of gifted students who are allowed to pursue individualized programs of instruction and inquiry. Although Hesseman famously trashed the show and seemed to think it didn't do enough to rise above being a mediocre, formulaic sitcom, I think his perspective was flawed. There were definitely stereotypical aspects of the show (the Lucy-Ethel antics of Dennis and Arvid, and the introduction of new and "sassier" characters as the series continued), but it was atypical and aspirational in other ways.
For starters, the show depicted an interesting model of progressive education, focused on Socratic discussion. In addition, at least in the name of the school's program (Individualized Honors Program) and in the way the students presented themselves (one had a computer, and another always sat on his desk), it also dramatized a model of student-centered learning that we have rarely seen on TV. In a more general sense, too, since many of the plots deal with Mr. Moore helping students navigate social problems and become more well-rounded individuals outside of the class, the series illuminated some of the problems that gifted students face, particularly when they are left to their own devices and presumed to be doing fine simply based on the evidence of grades. Advanced and gifted students often struggle socially, and they need assistance in realizing the potential of their gifts and understanding the larger importance of living a meaningful life. As the recent book Off the Charts reminds us, often gifted students, while advanced for their age, end up in more "average" position later in life. Such students need to be prepared for the complexity of such a journey.
The series also featured pointed political humor, timely for its day but now dated, such as jabs at then-vice-president Dan Quayle (of the three or four episodes I watched recently, every episode featured an insulting joke aimed at Quayle). If I remember correctly, poking fun at Quayle was sort of easy sport at the time, and probably not that controversial, but it was still more topical than most sitcoms were willing to be. (Since topical humor dates a show, it's often avoided in sitcoms seeking to preserve maximum syndication potential.)
Perhaps most importantly, though a subtle attribute of the show, in between the more personal plots and conflicts, the characters touched on and discussed many intelligent topics, with accurate references to Abraham Lincoln, FDR, World War I, and other historical events and persons. Even though this material was usually in the background or used as a humorous parallel (FDR and his relationship with his wife was referenced as two characters argued about their relationship, for instance), the allusions were not "dumbed down" and reflected careful and on-point knowledge and research on the part of writers. Sometimes, as in one episode that involved an extended allusion to Melville's short story, "Bartleby, the Scrivener," the intelligent reference point was even used as a turning point for the plot.
Hesseman thought the show turned out to be just another silly sitcom that didn't live up to its premise, because of its three-camera format, bright lighting, and insistence on formulaic joke timing, but it was this kind of content that elevated the series and made it brighter than most shows on at the time. Even a relatively silly romantic plot, such as the retroactively-famous episode involving a young Brad Pitt in a guest spot as the not-so-smart boyfriend of Maria, made an important, often-ignored point about the need for young women to own their intelligence and for all of us to be honest in our relationships.
Hesseman was wrong when he said that television would never aspire to become great or more daring than it had been in the past; since this series aired, we've seen a renaissance in quality-TV programming (alongside a parallel nadir in the form of reality TV). He also misjudged the quality of the show that he helped to make a success, even if it was only for a short while.
