This movie is a bit of a downer. The plot is hardly upbeat. It is a pessimistic story. Pessimistic stories can be engrossing-look at "The Treasure of Sierra Madre" for example-but, here, not all that much interesting happens. The performers do their usual shtick.. Sheridan, Bennett, and Mitchell are exactly the people you expect them to be, based on countless other movies. No great disadvantage, but no real advantage either.
Flynn is the main problem, but the problem is not with his looks. He appears older but still fit and handsome. He reads his lines and does his character well enough; his character is bitter and angry and cynical. But something very important is missing. The character is in no way likable. He is without humor, and, except for anger, without any juice, without any elan, without any positive emotion. We don't sympathize with him. We don't care if he repents.
Flynn looks unattractive because he plays an unattractive character. The movie has only a modicum of entertainment value primarily for this same reason.