The first sound film to be made by UFA - and they made the most of it including sounds from almost everything possible, vacuum cleaners, telephones, clocks, passing traffic etc.
Apart from a song that plays over the credits and reprised at the end, all the music in the film is diegetic, the pianist practicing in his room, but heard throughout the house. It's an early stab at realism.
Made in (almost) real-time, recording events of one evening, at least, in a boarding house, shown as if in real time.