The current benefits are massive because lung cancer, chronic obstructive pulmonary disease, and cardiovascular disease are the three biggest killers from cigarette smoking. Those conditions are, so far as any of us knows, caused almost entirely by constituents of tobacco smoke other than nicotine. It's not to say that nicotine is completely safe, but it's not the cause of the harm from tobacco smoking. So the benefits of electronic cigarettes are that if the entire population of smokers in Britain switched to electronic cigarettes from smoking tobacco, we would see the incidence of those conditions drop dramatically—heart disease in the very near future and COPD and lung cancer in the more distant future.
On October 28th, 2014. See this statement in context.