When i am in a hurry or have large mileages to cover they offer good value for money.
I agree. I'd rather pay a toll to drive on a well maintained and relatively uncrowded Autoroute if I need to get from A to B quickly.
Whats more, the tolls level up the playing field as far as the cost of rail travel goes. Already, rail fares in France aren't as outrageous as they always seem to me in the UK, but for a long journey, when you add the costs of driving (including tolls) it's almost always cheaper to take the train if you're on your own, maybe a bit cheaper in the car if there's two of you.