Zyban worked for me, in the summer of 2002. I was 26 at the time. I was a pack-a-day smoker, and the cravings pretty much just went away. I experienced heart palpitations the first time on the Zyban so I stopped it and went back to smoking, but my second time on the Zyban was successful.
A few years later, I briefly took up smoking mini cigars, one pack every 3-4 weeks. A couple months before my daughter was born, I simply stopped buying those, and I haven't smoked anything since. I never considered the mini cigars to be "falling off the wagon" because I never smoked them frequently enough to buy a new pack while I was in withdrawal from the previous pack. I'm probably bullshitting myself here.
Honestly, I miss smoking, I'm sure I always will. I enjoyed stepping outside for a five minute smoke break, even in the dead of winter. It gave me quiet time to chew on whatever problem I was trying to solve at work, and I'd usually return to my desk with a few new insights. Taking breaks like that now, without lighting up a cigarette, just isn't the same.