To be honest ever since Vodafone entered the German marked buying D2 Mannesmann the best advice was to stay away from them... go to T-mobile or O2.
Nothing to do with Germans in itself, my experience is just that Vodafone never delivered exceptional service or quality in Germany (can't say about other markets). The only thing which made them successful was that they took over the pretty great D2 network and lots of corporate customers.