I think they are better for smokers to use than regular cigarettes because the lack of tar and benzene derived chemicals means less likelihood of lung cancer and bowel cancer, HOWEVER (and this is a big however) the health problems and cancers caused by nicotine itself will still occur. More importantly is the effects of passive E-smoking on children and unborn babies will be the same. Children of smokers will still suffer from a much greater incidence of mental illness and probably asthema and ear problems too. What is more the liquid in E-cigarettes is extremely toxic to children if it is consumed, and there have already been incidences of death and hospitalization of young children as a result. Also the chargers appear to be a fire hazard.
On balance I think that if you are a smoker and do not have young children or grandchildren around all the time, then it might be a healthy move to switch, but these E cigarettes do seem to be even more dangerous to children than their traditional counterparts.
Love Sam x