This.

If you visit Paris now, you see more police, a slightly worse nightlife. Right after the attacks you could see everyone was really on edge.

On the other hand if you're taking into account this kind of mood/atmosphere, a place like Paris should be generally pretty low on that scale as people you interact with in your daily life seem a lot more stressed, tired, unhappy and sometimes aggressive than in any other French city. I know it's a stereotype, but it's kinda true.