Much better than I expected. Fleischer was a very crafty director and his skills are evidenced by the way he gave this story a pulse. And the production design is extraordinary, especially for the time. Most importantly, though, the film inspired two amazing Archer episodes. That in itself justifies the existence of The Fantastic Voyage.
Fantastic Voyage is nothing stupendous from a storytelling standpoint, but its more like a really adventurous science class educational film than a groundbreaking sci-fi movie. The titles were amazing and I loved the lighting and set design. Its some fun, entertaining eye candy.