Been to Paris a few times. Second trip someone slammed me into a metro car door and stole my wallet. Each time I went there were more and more immigrants loitering in groups on the streets, facing off with more and more police. Felt like a powder keg.

Most of the people that I worked with in Paris used cars or motorcycles; they earned IT and professional wages and could afford to avoid the prevailing public transport, which they did. Later the company I was involved with moved to a 'suburb' (not sure that's the appropriate term...) of Lyon. Huge improvement in every way and no one at that site used any public transport; all cars.

This was the early 2000's. I imagine the bad parts have gotten worse since then; if you look like a tourist or foreign worker don't go near the metro outside of business hours.