You cannot be in this region of France and go to this amazing place. It can be very busy, the streets are narrow and fairly packed with coach loads of people but the atmosphere is something else. Like other reviewers, get there early if you can. Don't wait until 12.00 for lunch, it will be packed. Choose a place before and get seated!
Take time to explore all the ramparts and narrow streets. It is a definite must do sort of place.