It is rather daring to present Thomas Mann's work ("Buddenbrooks", "Magic Mountain", "Dr. Faustus"), even on film, to the non-European audience because nowadays, hardly the native Germans dispose of the knowledge required to understand those works. Hardly any sentence spoken in the "Buddenbrooks" is free of allusions to classical Latin, Greek or German literature. If you do not know what E.T.A. Hoffmann's "Serapion" is about, you will not understand what is going on exactly when Grünlich is presented to the Buddenbrook family in the first episode and which is one of the major threads of the whole story.
The Buddenbrooks represent one of those highly educated and rich families which formed the Upper Class level of the German society in the 19th century. However, at the time, when Thomas Mann wrote his autobiographic novel, this was already past, since those families did not survive the time of the upcoming revolutions instigated by such theoreticians like De Tocqueville, Marx or Engels. Another strong feature, quite unknown in America, is the strict division of society in the Ruling Level on the one side and the "People" (= mob) on the other side. The world of the Buddenbrooks is the first level: One speaks a well-educated High-German, spiced with French expressions (French had been state language of Prussia under Emperor Friedrich the Great), one eats delicate food from plates made from Meissner porcelain, one has several servers. The rules of conversation and social behavior are even kept strictly up between family members (cf. the Gotthold story), even between husband and wife (because they come from different families which implies different degrees of ruling levels). On the contrary, the "mob" speaks Platt, a language typologically situated between German and Dutch (and the movie brings a few nice examples of this almost extinct language, although most people are not real Platt speakers, Rolf Boysen, born 1920 in Flensburg, excluded).
However, Thomas Mann's novel is not about the family Buddenbrook representing this highly educated level of ruling class (although he belonged to them himself and admired them his whole life), it is about their decline, and the decline of the Buddenbrooks stands paradigmatic for the decline of a whole epoch, which can only be compared to the decline of the Habsburgian society after the shot in Sarajevo which had been treated, amongst many others, by Joseph Roth in his "Radetzky march" which also has been filmed. For everyone not familiar with German history and, more important, with a whole continent which had been built on different levels of society and education, I recommend to read first the book and watch the movie after. Or watch Fassbinder's "Effie Briest", before you watch the "Buddenbrooks". I also recommend to watch Thomas Mann's "Zauberberg" (Magic Mountain), directed by Geissendörfer, as a preparation before trying to digest the heavy Buddenbrook stuff. And believe me: This movie, directed by Franz Peter Wirth, is well worth watching!