Dear Gurus,
Could you Briefly tell me what to consider if you would be to implement SAP French Payroll? What is easy? What is hard? Where to pay attention? Securité Social? Treizième mois? Arrêt maladie? E-comunication with French government authorities? Are there standard functionality specifically changed to comply with French legislation (such as retroactivity for instance)? I have a lot of experience on Spanish, British, US, Mexican and International payroll; so I would like to know if I am to expect the worst implementing PY-FR 
I know it is kind of general, but I am just looking for a “general” feel here.
Your Replies can either be in English or French.
Thank for Your help,
KR,
Antoine