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.)

True. There are very few places in the world where you can go without local language. It is a pleasure to see how this improves over years, pace of the change is dramatic, but we are far from there as far as Central and Eastern Europe is concerned.

How's the startup culture in Amsterdam and Berlin?

In Amsterdam there is a famously strong one, best in Europe (while nothing compared to the Valley). Berlin is also a nice place in this respect, i know a few guys in Eastern Europe who worked in startups there. Berlin is a very unusual city because while being a capital of one of topmost tech countries in the world, it enjoys cheap rent and cost of living/doing business (because it's not overcrowded yet, legacy of the separation era, quite opposite to say, London).

But what about Visa? From what i know there is no alternative like Europe Startup Visa.

You can always open a company and apply as a company manager. Also, you can get a Blue Card if you pay yourself at least 1.5x the average salary in a given country, which in the case of a funded startup should not be a problem. German immigration system is very kind to tech founders.