Pros
The company has tons of clients all around the world which is great if you're looking for an international environment. You also have to be flexible to accommodate for that international environment. You can work from pretty much anywhere in the country but being nearby a local office is better in my opinion to have access to resources and coworkers. The culture, the people and the company is pretty relaxed but you're expected to get your job done. The French culture is omnipresent which can be a great bonus. People and teams are technically competent and good challenges are available.
Cons
The French culture can also be a negative aspect of the company as it tends to favor clans and friends for promotion more than actual skills and desire for carrier advancements. On that note, some teams don't have any real possibility of carrier evolution. Compensation is not good and is not necessarily well adjusted to your location. The management doesn't try to retain their skilled people in any way.