Not much need be said but that this is a perfect performance of a perfect gem of the operetta repertoire - once a well-known concert piece, but now I suspect not.
The tenor is perhaps my favourite ever singer - Fritz Wunderlich (I first heard this on a compilation album of his). His earnest, ringing tone, and the way his voice opens-out as a musical phrase rises, brings tears to my eyes.
Anneliese Rothenberger was a wonderful lyric soprano. The dark-voiced bass, Gottlob Frick, was best known for playing giants in Wagner's Ring; here supplying a very low bottom note in the final chord (C-sharp or D perhaps - I don't have a score).
It is also amusing how German singers of this era (1961) really 'rasp'-out the consonants in 'nacht'! Almost a national pride at work, I fancy. And so different from the Italian operatic tradition, where the consonants are so elided that it sometimes sounds as if there are only vowels.