Pros
A wide range of areas can be explored during the career: social work, finance, HR, communication...
Internal (and external) mobility is encouraged
Great work/life balance
The Paris city council is a great administration to work for, with good values and culture, and offers a quite fast-paced environment considering it's public administration
Cons
Higher management is a ittle bit to clique-oriented
Experience can be radically different depending of the service you work for