I really like the taxi drivers in Istanbul. They are funny, friendly and helpfull...most of the time. I can tell you stories which you don't believe but simple are true. In contrary with the Amsterdam taxi drivers, also called 'the Taliban'. They simple navigate with their TomTom (nice Dutch invention) through the streets and act like bandits.
But there is one thing I really don't like about Istanbul taxi drivers; they don't speak English! I've taken taxi's in most of the European capitals, always they speak at least a second language (mostly English, sometimes French like in Italy and Swisse). In a couple of months Istanbul will be the European Cultural Capital 2010...in my opinion a bridge too far.