I watched "400 Blows". It definitely is an enjoyable and interesting movie. Truffaut received the Cannes Film Festival Award for Best Director for this film. It is also one of Sight & Sound's Top 50 films. And if you check wikipedia (assuming it is correct), " the French title refers to the expression "faire les quatre cents coups", which means "to raise hell"". According to the interviews in the supplemental material there really wasn't a script the actors followed, which seems amazing considering the performance given by Jean-Pierre Léaud. It seems he was given a description of the scene, what was desired and suggestions but the final words were his.
Another thing I found interesting in the supplemental material was Truffaut's mentioning American directors that he liked included Sidney Lumet, Robert Mulligan, Frank Tashlin and Arthur Penn. I find his choice of Frank Tashlin interesting. Frank Tashlin directed "Cinderfella", "The Geisha Boy", "Rock-a-Bye Baby", "It's Only Money", "Who's Minding the Store" and "The Disorderly Orderly", all Jerry Lewis films. Tashlin directed many other films but I think there are a lot of people who might question the greatness of these films. Tashlin was also mentioned by Mark Cousins in "The Story of Film". It seems to me, at least to a certain extent that Tashlin and Lewis are more admired by certain people who live outside of the United States. Interesting. I'll have to go back and watch these films. Tashlin also directed "Will Success Spoil Rock Hunter?", "The Girl Can't Help It", many other films and a lot of shorts, including a lot of Porky Pig cartoons. Interesting.
Roger Ebert review
New York Times review
400 Blows wikipedia entry
400 Blows & Truffaut