ecigs cannot be a successful way to quit unless you have the committment to gradually lessen the nicotine and eventually stop and then, unlearn the hand to mouth to inhale process. most will just remain addicted to the whole smoking process and many will go back to smoking the real thing.
ecigs can't help you unlearn the habit or break the addiction, they actually reenforce it.
you are still pretending to smoke and you are still hooked on the drug.
there is of course an advantage to the manufacturer.