For quite a few people, nicotine provides the benefits that some people get from caffeine or Ritalin: it helps them focus and be more productive, overcoming attention-deficit-type problems. For some people, nicotine provides relief from stress, anxiety, or panic. For people suffering from some severe mental illnesses, nicotine seems to provide great relief, which probably explains why a very large fraction of psychiatric patients smoke.
Nicotine is also suspected as the reason for the lower incidence of Parkinson’s Disease among smokers. And for those who have it, nicotine appears to reduce the associated symptoms.
Laws against smoking in public places are often praised by anti-smoking advocates for making it easier for smokers to quit. But when you start pretending that smoking has no benefits, it becomes clear that making quitting “easier” really means making smokers’ lives so unpleasant that the costs exceed the benefits, even when the benefits were high.
Having said this you have to weigh up the cost of using nicotine. To use nicotine you have to smoke and this is where the problems occur. Along with nicotine is a huge cocktail of some very nasty chemicals which have a huge impact on your health, a cost that can lead to some very unpleasant and often fatal effects.
Whilst nicotine itself can have some beneficial effects the negative effects of smoking far outweigh them. The fact of the matter is that whilst nicotine per say may not cause an increase in cancer or heart disease smoking does.