I scored 27 out of 33 in the online sample test in the Spiegel website. I only have a thin slice of knowledge of German history and society. I just learned most of my German knowledge when I arrived here. With a combination of luck and common sense, I think one could easily get a passing score of 17.
The test is a combination of history/politics (who was the first Chancellor of Germany?), culture (what do Germans do on Easter?), and law (What is the name of the German constitution?). Most of my mistakes were objective type questions dealing with dates and places.
There were debates previously on the difficulty of the first version of the test, that even Germans who took it actually failed! Now they say it is too easy to become a German based on the 99% pass rate. Maybe the Foreign Ministry needs to increase the hurdle rate for German citizen-aspirants up to 25 correct questions, and to recite a line or two of Goethe’s poems. In German. Or monitor the number of times in a year one had to run after a tram to measure one’s punctuality. Decide for yourself, and see if you deserve a citizenship to the land of beer and bratwurst (sorry, no questions on those). Viel Erfolg!