Even if it won't give one more than previous posts here (like Ruby Liang's very good one) i wanted to share my own point of view. Hope my English is understandable.

Bon voyage is a rhythmic, light but deep presentation of the French unorganized come-down, but also courage and charm. All along in a brilliantly reconstituted 1940 France with many details (from Bordeaux luxurious hotel occupied by Government HQ and attacked by useless high class French, to Parisian coffees near Le Pantheon / rue Mouffetard and 1930s cars) Gérard Depardieu and Yvan Attal give their second roles a brilliant taste;) Isabelle Adjani and Virgnie Ledoyen are very credible in their drastically different roles, and Grégori Derangère makes an bewitching performance:)

Much lighter than average (e.g. American) war times movies, and focused on the civilians, Bon voyage shows a lot of things about french issues (even to a French guy like me), some of them quite deep.