C&P technolgy is not "very new". It has been used in Europe since the early 1990's. There is no reason for teething problems, the UK banks should have had everything sorted out before launching on such a massive scale.
I may appear extra bitter about this - that's because my new UK C&P card worked once with the PIN number I was given and then it failed. I didn't alter the number. A replacement card wouldn't work at all. It is quite humiliating to be in Tesco trying to pay for a trolley full of shopping and being considered almost as a criminal because some piece of unreliable technology is demonstrating its unreliability.