The cities within the Ruhr area are amoung the safest in Germany. Since the Ruhr area has fewer tourists, it is not in the focus of pickpockets. But it is still a good idea to take the usual precautions. Never leave your camera unattended or flash around a fat wallet. Since many citizens are from elsewhere, strangers are widely accepted and the chance of encountering racism or other prejudices is low. Because of unemployment and the demise of the once excellent German social system, beggars and bottle collectors are becoming rather common problems, but they are usually harmless.
talk
The pronounced Ruhr dialect Herbert Knebel Dr.Stratmann, Atze Schröder of the 20th century is generally disliked and is hardly spoken. The openness of the people of the region is shaping now a new dialect, which was enriched by linguistic and grammatical elements of the immigrants from 167 nations.
Do not expect that everyone understands English, although most people have had English lessons at school. You will have fewer problems if you are able to communicate in German. But communication in English is possible if you do not hesitate to ask the next guy if the first one does not understand you. At some quarters you will find a lot of people able to talk Turkish and, according to the immigration of the last decade, some guys with Polish or Russian. Other languages are not very common.