How are blacks, black Americans if that makes a difference, treated in Germany?

Avoid EAST GERMANY!

bs volldepp, i live in europe and i know that Blacks get killed in small towns in Eastern Germany. It is naziland after all, they havent changed and dont expect that. Be careful and always make sure you let them know you're American so they wont mess with you.

He'll have 'fun' over there since he speaks the language.

Please don't trust this no-go-area claims. Translate the text which is linked by Aaron and you will understand that it is rubbish. Speaking fluent German is very good. However, if he has not been to Germany before, maybe his German is not as fluent as you expect it to be ;) Rammstein is most popular outside Germany, so don't wonder when German people don't share that interest. Don't feel offended if somebody stares at you. You may look uncommon for them. So as a white person is uncommon in Africa. However, I also think that it could be a it more easy for a black American than for a black African. The cultural differences are simply smaller. Enjoy the stay!

Not so different than the US, but I reckon the east is more old-school racist still, since they were shut out of immigration by africans so long. There's a minority of racism there like here, but also a lot of that euro liberal goodness too, even better than US in ways, I think.