It mostly sounds authoritative, unemotional, and sadistic.
But I'm talking about their regular everyday speaking: https://www.youtube.com/watch?v=ghRKZRcxeI4
That's how it sounds in everyone's ears, in countries with more melodic languages like Spanish or French.
(It's not even the pronunciation overplayed in the video for comedic effect, many words are already threatening sounding by themselves, just the letters on page invoke either threat or bureaucracy).
Basically captures that part you said "I agree that German isn't the most pleasant language".
Sorry, Dutch and Turkish friends.
Turkish does have some harshness.