"Fantastic!"
I loved this tour! Very well organized. All went smoothly. The departure is at 9am from the Agency on Rivoli street. When you get in the bus the company representative gives you a program with your name on it and entrance tickets to both castles + tickets for audio guides. Before we left the lady explained the route/bus stops/times in French, then asked who speaks a different language and explained once again for certain tourists in English and Spanish.