I'm certainly no "expert" but spent 9 years in Germany and Austria, learned German at the Defense Language Institute.
EvaBrick gave some good comments. But, Germans vary a great deal due to which part of Germany/Prussia they come from. And, there are some strong regional biases. I was there before the fall of The Wall so cannot talk about those who lived in the east.
Generally, I found Germans to be very formal with strangers or even those outside their social circle. But, within the family, they are quite open and fun-loving.
Austrians, on the other hand, while German, are far more laid back and receptive.
In both societies, class/status plays a huge part in interaction.