Arguably one of John Huston's finest films ever made and until The Last King of Scotland was released (several years ago), it was the last movie filmed in Uganda. Despite not being rated by the MPAA, I suggest that children under 10 not watch this movie but not because I find anything in it potentially offensive, but rather because the movie is very dated and very much a product of it's time. Younger children will have no idea what it's about, what's going on in world history at the time, who the Germans are (and why they're the bad guys), etc.
Charlie Alnut may be a good-old-boy, but he is a drunk and chain smoker (Bogie always smoked in his films and frankly never made it look so cool). Katherine Hepburn's character (Rosie), being a missionary in Uganda (1917, I believe), tries to change Charlie's behavior throughout the course of the movie and arguably succeeds. If you're a Christian, you'll like her strict morals and how while she's determined to destroy the Germans' boat ("The Louisa"), she still has strong moral principles that can be applied to everyday life. Ex. Drunkenness is bad, prayer is powerful, being a missionary is dangerous but very rewarding, etc. I first saw this movie when I was probably 10 and didn't really get it until I was probably high school age, but that's only because I didn't have the historical background to fully understand the movie. At any rate, it's one of the great films to come out of the 1950s. I'm sorry it took Fox and Paramount so long to come to an agreement in order to get it out on Blu-Ray and DVD. The latest restored version is breath-taking and looks and sounds better than what I imagine it did in 1951.
What other families should know
Too much drinking/drugs/smoking
Great role models