A lot of things about this film make you think director Ralph Thomas slept his way through the job. The scene when Donald Sinden tries to push off a mine with his feet is amazingly badly done. The film also fails to give you a real sense of what the mission achieved! (It did not, as the film implies, break the back of the ship -- but did succeed in putting Tirpitz out of action for half a year; the RAF finally destroyed her a year after the midget attack.) But there are plenty of decent scenes, and some real tension. The script isn't bad, and having the Germans speak in (unsubtitled) German adds authenticity. John Mills is, as always, excellent. Above all, the film tells a true story, of primitive, cramped baby submarines, poorly insulated diving suits and icy water. And real heroism.