The card is issued by Advanzia Bank which is from Luxembourg. The main issue with the card is that you have a seven day limit to pay your credit card bill or they charge you ridiculous fees and interest rates. While it is common in Germany to pay off your credit card bill every month it is normally done by automatic deduction from your bank account. With this card you have to make manually a deposit. So you have to very careful not to miss the deadline every month.

I also use DKB, especially to withdraw money for free. That's how I get money from my German bank account to my US bank account for free. It works great.