It wasn't effective at all, in fact the numbers of smokers went up while the Nazis were in power. Germany did lead the world in anti-tobacco use campaigns as well as research of the negative effects tobacco had on health, but that began well before the Nazis took power.

While the anti-smoking campaign in Nazi Germany was highly touted, anti-smoking laws were routinely ignored, poorly enforced, and pretty much useless. Their effectiveness was marginal at best, and after 1940, was heavily restricted by the government.

The Nazi Party actually made a huge amount of money from tobacco sales, and controlled the market. You might find this interesting. Sturm Cigarette Company