They have worked for many smokers and are relatively safe, esp. in comparison to tobacco cigarettes. They have been recently featured in a New York Times article -
http://www.allecigs.c...electronic-cigarettes
To quote the NY Times article: "No one knows exactly what long-term benefits they’d gain from e-cigarettes, but we can say one thing with confidence: Every time they light up a tobacco cigarette, they’d be better off vaping.”
Vaping refers to using electronic cigarettes - they emit water-based "vapor", instead of deadly tobacco smoke...