[erispoe]

And what problems are they exactly? Are they making prior residents worse off? Or are we talking "cultural danger"?

There is no evidence of the former. In fact, a large part of why Germany has taken so many immigrants compared to other european countries is that the german workforce is stretched thin and needed an influx of young workers. Plus Germany has more infrastructure in place to integrate foreign population.

If we're talking the latter, then that's irrational fear.