In a world where we are all used to plastic covering everything Germany stands out as being rather hard-cash based. Quite eye-watering to fill the tanks only then to find EC Card (a German only throw-back) or cash
They are slowly getting more 21st Century about this, but worth checking first.
ATC is great and very helpful; food is great - even the black bread, which is worth processing first; too many sights to see - I don't know where I'd start, but I'm told Koblenz airfield is worth a night-stop.