From my experience, people get along pretty well in Germany even if they know only English. Especially in large cities like Berlin, where they are likely to get such a job. So many people speak good English here, that it is actually hard to learn German, because the natives don't want to speak German with you :-). I'm in research, and half of my institute here in Berlin are foreigners.

Of course, it still helps a lot to learn German - and I think you miss out on a lot if you don't learn the language of a country. Also, you'll need a friend or colleague to help you with administrative stuff in the beginning (which may be in German only).