The only warning I will give is one for driving on Bundesstrassen, the 2-lane roads outside the city. Also bicyclist are using these roads where cars sometimes drive with speeds up to 100 km/hr.
From both sides: Be prepared!
As obviously mentioned in the Lonely Planet Guide Germany or Europe (which was a big issue in the papers up here!) it´s not always too easy for ethnically different looking people to enjoy this town! Be prepared to be kind of harassed by some assholes! As long as you´re in groups and don´t go to certain quarters in the outskirts you should be fine, but I wouldn´t guarantee for anything.
It´s very sad and making me angry, too but I am not the only one beeing without any idea what to do against that (effectively).
Watch out! Otters may cross the street. Have you camera at hand!
The bottommost sign means that the local otters are 100m tall! (just kidding)
Driving along the coastal roads you see a lot of these funny signs.
I guess this means badgers may be crossing street.