One of the last big sci-fi pictures before 2001: A Space Odyssey came along and fundamentally changed the possibilities of the genre, 1966's Fantastic Voyage is the platonic ideal of a movie that gets praised, sincerely, for its visual effects, by someone whose tone of voice and inability to maintain eye contact make it clear that they hope you don't ask about anything else. Because it feels bad to attack the movie: the visual effects are really good, even if they were supplanted and then lapped within a few years of its release. And how much nicer to have those kind of top-drawer visual effects in a movie about interesting concepts and adult characters, and not one that involves giant robots walloping the shit out of each other.

Still, you can't get too far into the film before you have to admit that for all its achievements, and the very real charm of mid-'60s sci-fi (notwithstanding the vast budget gap, the film more than slightly resembles TV's Star Trek, from the same year), Fantastic Voyage is a fucking slog. It shouldn't be: the hook is terrific. Both the U.S. and the USSR have developed miniaturisation technology, but only the Americans have a scientist who knows how to make the process last for more than an hour. And he's been almost fatally shot, and sent into a coma that can only be cured by shrinking down brain surgeon Dr. Duval (Arthur Kennedy), his assistant Cora Peterson (Raquel Welch), Dr. Michaels (Donald Pleasance), and sub captain Bill Owens (William Redfield), and injecting them and their microscopic submarine right into the scientist's body, with government agent Grant (Stephen Boyd), along for manly protagonist duties, trying to catch Duval in the act of being a Commie spy.

That certainly ought to be a fantastic voyage, and if you've encountered the story in Isaac Asimov's novelisation, you even know that it kind of can be (Asimov demanded permission to re-work the story to make it less idiotic). But Henry Kleiner's screenplay and Richard Fleischer's direction show off all the seams and plot holes while pushing the plot along as slowly as a nominal adventure movie could possibly support. The sub voyage takes place in something longer than real time, during which the plot plonks along through a repetitive cycle of theoretically tense moments flattened by lifeless direction. Every actor who isn't Pleasance stands around being vastly too serious, and sometimes we are given blessed relief in the form of the production designers' florid, psychedelia-tinged vision of the inside of the human body.

It looks great - there will be those who carp about how dated it is (and, sure, it is), but really is quite a special visual experience. Tragically, behind those visuals, it's bloated B-movie nonsense built around false characters, expanded and perpetrated by people who didn't know how to capture the proper spunk and speed of a good piece of junk sci-fi.