I've heard of several people that were able to quit by using the e-cigarettes. Dr Oz said that some of them contain antifreeze though. That is pure poison.
In the next year, the congress wants to pass legislation where they will start checking the ingredients in them before they are sold. They also want to make it illegal to sell them to anyone under the age of 18.
At that time, when they are safe and minors can't purchase them, I think they will be beneficial to adults to quit smoking. I've tried them myself and at least they would prevent lung cancer. I am afraid to use them after hearing about the antifreeze ingredient though.