IT Professional in Munich

I'm a freelance IT developer/consultant, English native speaker, and I got away with only speaking English my first two years.  After that, though, and as I moved up the ranks and started working for myself and acquiring customers/managing projects, German seemed to be a HUGE help and definitely a game-changer when a company is thinking of hiring you.

However, most large companies have English as their business language.  But if you're leading a team of German developers, you might find it hard to communicate with them about everything.  There are also some instances where English is a plus.  I've managed projects from teams in Russia, Ukraine, Netherlands and the USA, and it really helped there that I had a command of the English language and could converse in English with non-native English speakers as well as translate the information to my German colleagues.  It's a funny/interesting thing to have non-English speakers discuss IT-topics with each other as each language expresses things differently.  I remember once someone from India and someone from Tunisia trying to talk about the URL, but their differences in dialect made it difficult for us to understand that we were all talking about the same thing.

In any case, definitely make the effort to learn German.  It's rewarding and Germans look favourably upon it.