Although the Broadway musical "It's a Bird...It's a Plane...It's Superman" general received positive reviews, it closed less than 4 months after it opened (only 129 performances from March 29-July 17, 1966). Obviously, it didn't quite grab the theater-going public's attention, even with the enormously hot Batman series that had been running since January.
So why ABC decided, 9 years later, to produce a late-night TV-movie version may never be known. And having had no exposure to the live-stage version, I can't imagine what changes they may have made, but this movie was all kinds of suck. One indicator of how bad it is/was: ABC ran it one time in their 11:30 Wide World of Entertainment time slot...and hasn't been rebroadcast since.
It starred David Wilson as Superman/Clark Kent, who went on to, well, nothing very notable, and Lesley Ann Warren as Lois Lane, who has actually done quite a bit since then. It also featured Loretta Swit as Sydney, recreated the role performed on Broadway by Linda Lavin.
In order to comprehend the horror, you just have to experience it. Here are a bunch of clips from the movie, starting with Loretta Swit singing "You've Got Possibilities," which isn't completely horrible...but it only gets worse from there: