Nicotine itself (without the byproducts that happen when burning tobacco) is not even that bad [1] (deadly in relatively low amounts but unless you take it concentrated it's very hard to reach those levels). Unhealthy? Yes, but probably not much worse than caffeine [2].
Besides, Nicotine itself is not that addictive "Technically, nicotine is not significantly addictive, as nicotine administered alone does not produce significant reinforcing properties. However, after coadministration with an MAOI, such as those found in tobacco, nicotine produces significant behavioral sensitization, a measure of addiction potential." [3]
[1]: There are a few studies that look at nicotine excluding cigarettes on Google Scholar.
Cough, was that completely honest? since you linked to Wikipedia for Nicotine, I suspect you did know you'd get lots of really good effects by linking to Wikipedia for caffeine. :-)
Wikipedia had a lack of harmful effects of caffeine (or at least none written in a way I as a layman can understand) and I thought a site with articles about caffeine selling caffeine products would make an okayish substitution.
Again for nicotine there is no convenient list on Wikipedia, so:
> In one study, a group of Alzheimer's patients were given nicotine patches, while another received a placebo. Those with nicotine patches maintained their cognitive abilities longer and sometimes even recovered lost cognitive function.
> Contrary to popular opinion, the study showed that nicotine actually boosts the growth of new blood vessels.
> In 2006, Duke scientists found that people with depression who were treated with nicotine patches reported a decrease in their depressive feelings. The results were perhaps not surprising for a drug associated with imparting a "buzz." However, the research also showed a direct link between nicotine and an increase in the release of dopamine and serotonin, two vital neurotransmitters. A lack of dopamine or serotonin is a common cause of depression.
Besides, Nicotine itself is not that addictive "Technically, nicotine is not significantly addictive, as nicotine administered alone does not produce significant reinforcing properties. However, after coadministration with an MAOI, such as those found in tobacco, nicotine produces significant behavioral sensitization, a measure of addiction potential." [3]
[1]: There are a few studies that look at nicotine excluding cigarettes on Google Scholar.
[2]: Compare http://en.wikipedia.org/wiki/Nicotine#Pharmacology and http://www.energyfiend.com/harmful-effects-of-caffeine
[3]: http://en.wikipedia.org/wiki/Nicotine#Psychoactive_effects