This is the third court that the complaint, originally lodged by the Federation of German Consumer Organisations (VZBZ) in 2010, has been reviewed at. All three courts have ruled the same way. The laws Facebook is breaking come under data protection and unfair trade practices. Now something will have to change.
Facebook isn’t saying much yet beyond waiting for the formal decision to come through so they can take any relevant action. That action seems likely to be the friend finder feature disappearing in the short term from German Facebook accounts. Whether it returns depends on if Facebook can stop breaking the specific laws the courts refer to. However, it could become a much bigger issue for Facebook if other countries use the German ruling as a basis for taking their own action.