Today this is one of the most famous of Manet's paintings but when exhibited for the first time it was a scandal. The naked woman was the reason. After the post below it is funny to think it was a scandal but at that time naked women in paintings were not a contemporaneous woman as this one. She is a woman of that time and this is one of the reasons people thought it was immoral.
If she was a goddess there was not problem but she stares at you without any shame and how dare her being with two men?