I don't have a large sample size, but my small set of second-hand reports suggests that trying to live-and-work in Berlin can be problematic if you don't speak

I don't have a large sample size, but my small set of second-hand reports suggests that trying to live-and-work in Berlin can be problematic if you don't speak at least passable German. Not for the startup scene itself, where everyone speaks English, but for practicalities like interacting with the civil service, health-care system, housing, and banks, where German is expected. (This is a difference from Copenhagen, where everything can be done in English if you prefer. And Danes often prefer it, too, because they don't understand foreigners who try to speak Danish.)