At the site a tip: When a coffee / espresso is actually bitter, the grind may be too hot to fine or the water when boiling.
Since the coffee both my wife and me have to taste, we have not decided on the Gorilla Superbar Crema but still tried Joerges Gorilla Crema No.1 1 kg beans and Gorilla Espresso Delicato 1kg from the same roasting. The two other coffee taste even my wife, so that we now can not decide really us, what sort we reorder. Presumably we will reorder both varieties and so every now and then something can alternated.