Although it's been a few years since I lived in Germany I strongly disagree with this sentiment. I never had a bad train trip and I took them semi-often for work via Berlin-Munich and many times for pleasure around the country and continent. They far surpassed those in Eastern Europe for instance (although the train from Romania to Moldova was fun partially because it felt like time travel into the Soviet era)
I had quite a few bad trips. Two of them left me at trainstations without any other transportation method (one of them was an fallen tree and the other an broken train). My median for delayed trains gets smaller but is still in the 15 minute region.
