One thing I hate about being in France is all the smokers. About 1/3 of the people here smoke and they do so with great frequency in the streets, in cafes, in restaurants. The worst offenders are young women who (I'm told) smoke to stay thin. I literally tense up anytime I'm in a nice outdoor café and a group of young women sits next to me. My eyes start scanning for the cigarettes (Marlboros, usually) and I start judging which way the wind is blowing.
French restaurants are all supposed to have an espace non-fumeur, but often that doesn't work very well. And outdoor seating pretty much always allows smoking, more of a problem than you would think. In better restaurants there's often an understanding not to smoke near diners, but it's dicey. After years of living in smoke-free California I'm simply not happy tolerating noxious exhaust anymore.
In theory in 2008 this is all going to change in France when the rest of the non-smoking law goes into effect and smoking is banned in cafes and restaurants. Assuming the law survives today's election, I give it about 50/50 for actually being applied consistently.