I thought TH&TM was a pretty decent film. I saw it originally in a cinema shortly after it was released.
From Wiki:
Gann wrote, or adapted from his books, the stories and screenplays for several movies and television shows. For some of these productions he also served as a consultant and technical adviser during filming. Although it received positive reviews, Gann was displeased with the film version of Fate Is the Hunter, and removed his name from the credits. (He later lamented that this decision cost him a "fortune" in royalties, as the film played repeatedly on television for years afterward.) He wrote the story for the television miniseries Masada, based on The Antagonists, and the story for the 1980 Walt Disney movie, The Last Flight of Noah's Ark