I live in Munich, Bavaria, and, to give an example, in most restaurants you will not be able to pay with a credit card. Having said that, you can pay once you reach a minimum amount with what they call an "EC-Karte", a sort of debit card.
"I'm supposed to pay my dinner bill at a fancy restaurant.. in.. cash?"
Nor will they - unfortunately - accept reservations in English.
As a side note, I also use my German EC card abroad. Fees are surprisingly low and it is accepted in more countries than you'd expect.