Another long disputed question: are Kraftwerk a prog band? Once again, I don't know. For sure, this track contains may typically prog features, such as highly creative keyboard sounds, tempo and mood changes (yes, Kraftwerk did so more often than you think) and a very good melody coming in several variations. As the band only employed electronic instruments, you won't fine here the most usual rock highlights: no guitar solos, nor physical drumming here.
How could we forget these guys...
...or this single version of the song?
That said, no one before or after them took such an advantage of vocal filters, special audio effects, drum programming and so on, turning each song into a musical adventure... and this is exactly what prog is meant to be. And I like this song in particular for its romantic rendering of electronic music... am I too smoochy?