This is the cheapest option if you are in Paris, which isn't saying much. We'll actually there's a place two doors down that had sandwiches in a display case but for an extra dollar or two we got a much more appetizing sandwich here.
I definitely would not go out of your way for this place. However, if it is 2pm, you just got in from your flight and don't want another airport refrigerated sandwich, then just maybe this is the place for you too.