Everyone likes Flebus. Until he meets someone who doesn't.
This is one of those cartoons which connoisseurs of animation like, but which I don't. It's well written, and the voice work is prime -- Alan Swift does all the voices, starting with a narrator who sounds like Sheldon Leonard. Where it fails for me is in the visuals, the sine qua non for cartoons, indeed, for all movies. The character design is abstract, the background minimal, and the animation just about non-existent.
The Gene Deitch era at Terrytoons was viewed as a flowering of new technique. To me it looks like a time of desperate scrambling, as inflation, crashing budgets, and new corporate bosses collided. There were good scripts, yes, and Flebus has one. But once the images are gone, it's of no real interest beyond radio.