I'm afraid I can't speak for how effective they were, hopefully someone more qualified will answer that (it's quite hard to quantify the effects of propaganda, and any conclusions are hard to prove either way). However, I hope I'm allowed to provide you with an excellent resource showing what they said.

You can see for yourself here: https://www.psywar.org/leaflets.php

Specifically, the section of German leaflets in English might interest you (unless you know one of the other languages): https://www.psywar.org/apdsearch.php?po=3901