My dad went to see it in theatres at 8 years old (in french in Quebec) and he was so scared during the boat scene that he ran out of the theatre to his grandmother's house. Growing up I always heard the story of the super scary movie "L'Homme H" but my dad only tracked it down recently on a "Toho Collection" Blu-Ray. We watched in and it was pretty good for a pre-Godzilla Toho movie.