I suspect this movie grew out of the phenomenal success of Dany Boon's previous movie, Bienvenu chez les Ch'tis (2008), which set box office records in France two years before. That movie was about cultural differences between middle-class Frenchmen and the Ch'tis, the French who live in the far northeast corner of France (what was once the Nord Pas de Calais and is now trying to come up with a new name for itself). That movie plays on cultural stereotypes, true, but it is often very funny.
This one is less funny, frankly, though not without laughs.
This time the clash is between the French and the Belgians. More specifically, it is the story of a family of rabidly anti-French Belgians and the problems they cause for one of their own, who has had the misfortune to fall in love with a Frenchman (Boon). The jokes are usually pretty obvious, but the characters are generally likable - with the exception of the Belgian border patrol guard, who is just too extreme.
You won't be bored, but I can't imagine you'd come back for seconds.