Yes, that's true. The Germans are really stiff, as well. Immigration of course here in a very hot topic, because of the history..we are therefore also quite lenient in many ways, too lenient in my opinion, but I'll leave it at that.
My parents also immigrated, they fled from the Iron Curtain. But my father went to Uni with very little german at first, but he tape-recorded the classes and my mother would later translate it at home. Some people and groups integrate better than others, especially to be seen after 2 or 3 generations.
The new guys who come who are fleeing from wars/dictatorship in Africa are all very friendly and smart, regardless of religion and such bullshit, and there is a lot of support from the german society on an individual level. But there are so many implicit rules and behaviors of what is considered impolite or when you are friends etc. that foreigners also have a hard time to 'become German', like you wrote 'can't really become Swedish', I imagine the same thing.