I don't smoke - in fact I detest smoking. But each to their own, as long as they don't blow their smoke in my direction.
Some things I dislike about some smokers:
When they say "I smoke because it relaxes me" - bollocks
It only has a relaxant effect because without the Nicotine (which is more addictive than heroin) you are in effect going through mild Cold Turkey. When you get the Nicotine back inside you, all is well.
When they say "I smoke low tar cigarettes, so they are better for me" - again bollocks
When someone smokes lowtar cigarettes they tend to inhale much deeper in order to get the same effect, this means the smoke goes deeper into the lungs - not good.
When they say "Smoking is cool" - bollocks
It may be cool to some 15-16 year old kid (which is the group the tobacco firms target), but to anyone the least bit grown up, smoking is about as cool as watching a film where the word shit is used, y'know it doesn't register as good or not, just mediocre.
One benefit of smoking is that it is thought to help minimise the risks of suffering from both Alzheimers disease, and Parkinsons disease. This is due to the Nicotine stimulating the brain in a certain way. Drugs were under development, and I am sure still are that take the beneficial effects of the nicotine, whilst negating the negative effects, this would be useful in the treatment (though not cure) of these terrible conditions.