During the last decades, the English language had a huge influence on German language. People almost automatically grow up with a few English words which are used quite extensively and s lot of English pop music is heard around here, more than in any other country, I presume. So you already get acquainted with English from birth. It depends on which generation you look at, of cause.
As already mentioned here, both languages have a lot in common, as they come from the same Germanic lineage in many ways, so the effort to learn it isn't that big compared to other languages and English often has a much simpler structure as German, e.g. 'der, die, das', the genders and all those cases even Germans often have their problems with. But you need to learn your vocabulary like anybody else in the world who wants to learn a foreign language. There are also a lot of people who learn Latin here and a lot of words in both languages stem from Latin.
I wouldn't say, though that someone who comes from Southern Germany has it easier to learn the language. The Northern German dialects, called Low German, have much more in common with English than other dialects in Germany, but they are seldomly used today.
People from the Netherlands have the least problems with English, as Dutch has even got more in common with English and the Dutch don't have all their English tv-programmes and movies dubbed, unlike us Germans have, and the relations between the UK and the Netherlands were vaster in the past couple of centuries.
So it's quite easy to learn English for us Germans compared to other non-Germanic languages. But more than that, a lot of people who travel a lot even know a few words in other European languages, because compared to America, everything is just around the corner. You can just hop in a plane and there are dozens of countries with different languages within one hour reach. From the place where I live, I can easily reach the Netherlands and Belgium by car, three hours tops and you're in Belgium, one hour for the Netherlands. And all those countries grow together, you can't see borders and checkpoints anymore between a lot of countries, it's quite fascinating. And Germans in general really tend to travel a lot and English is the first foreign language everywhere, the modern 'lingua franca', so it's quite useful to learn it. I think it's somehow comparable to those people living closer to the southern border in the US. More and more people are learning Spanish or at least know a few words here and there.
But I have to admit, the average German mustn't necessarily speak English fluidly. You learn it at school, but you constantly need to keep it active by using it. I think the Dutch and also people from scandinavic countries have a much better proficiency in English. As already mentioned, in Germany every teeny tiny bit of English is dubbed. All the other countries with Germanic languages simply use subtitles or nothing at all.
Btw, here's an interesting wikipedia-article about 'Denglisch': http://en.wikipedia.org/wiki/Denglisch