I think it is good if they can get teenagers to not to start smoking before they start with programs in a school etc.. that teaches them about the effects of smoking after all who wants their children to start smoking anyways? This sort of thing has to be aimed at the right age group whatever the age it is that most do start smoking.
As an adult though I feel it is our own right to do what we want with ourselves whether it be smoking, drinking, partying, sex etc.. the same as those religious people coming and telling me what religion I should follow. I feel it is my life to live and no one is going to live it for me accept myself.
Bottom line though I say that if you can stop a teenager from starting to smoke then that is all good.