The first film in the Gamera series is the only one to be made in black and white. The English language release also changed the spelling of the turtle-monster's name, apparently so that it was obvious that the 'a' was as in 'hat', rather than as in 'hate'.
It's also likely that it's the only film in the world to feature a father tell his son 'stop obsessing about turtles and focus on your schoolwork' in the sort of tone that suggests a drug abuse intervention.
This scene is presented entirely straight-faced, and is one of two sequences in the film that gave me the giggles (I may have been saying things like 'You gotta get off the turtles son, before they fry your brain, or you'll never get your life back on track!'). The other giggle-worthy scene is the conclusion, but I won't spoil that: you'll have to see it for yourself.
The film's final point of uniqueness is being the only one in the franchise that pits Gamera against humanity. In later films, the rocket-powered turtle is generally benevolent. Not that he's actually malevolent here, either. He's just very big and very hungry, and his food-source happens to be energy (especially fire) which leads to a lot of destruction as he snacks on power stations, fuel depots, and dams.
All in all, the film's a fairly transparent Godzilla knock off, though as a kaiju, Gamera's quite a bit goofier than the OG.