Pros
The surrounding area is a nice place to live with lots of things to do. Many facilities are available for employees, kitchens, a good canteens, as well as social clubs and services.
Cons
The technology is very old and the code is among the worst I've ever seen in a workplace. Staff turnover is high and they like to employ young people from university who leave after a few years so the quality of the code keeps getting worse. You are restricted from using new technologies and have no freedom to implement anything. The company is more interested in how much you love the company and it's bad inefficient processes than how well you work. The company likes to keep a high number of contractors and often there are bad feelings about the way contractors are poorly treated. There are too many managers who seem to do nothing except receive reports from team leaders. The company is stuck in old way and have become too big and inefficient to change. A lot of work (new and old) is being outsourced to cheaper countries. Promotions are based on which university you went to (even if you have 10+ years of high quality experience and high technical skills). With an odd exception, only French people are considered for leadership roles.