I must admit I was surprised by my recent taxi experiences in Paris. I'm one of those who has always said don't worry, anyone who deals with tourists is going to know some English. That was not the case in the 3 taxis I took, the drivers were nice enough but rather clueless about directions and did not know English. Luckily I had my confirmation printout of our hotel so we were able to show him and give him the exact street and number. Some have GPS, some don't, some don't seem to care to use it. One guy did in fact use his GPS to great effect so hats off to him.
Also surprised that they do not accept credit cards. My last visit was many years ago and back then we used cards all the time. This time we asked the concierge as we waited to go to CDG if the cab would take a card. He smiled and said no, make sure you have enough cash.