Zyban imho is no fun. Tipped me into a serious depressive episode a few years back coupled with high blood pressure. No fun - I would suggest that people avoid it like the plague.
I tried this about 6 years ago. Got the entire 3 month supply by mail order under my insurance program (over $300.00 worth) and it all ended up in the trash.
Let me just say that when I opened the bottle it had the most unpleasant aroma, like that of a person's hair that was undergoing a permanent wave.
I only ever took 2 tablets. For the next 24 hours I experienced hundreds of mini seizures. I tried to sleep through it with my entire body convulsing like I'd received an electric shock about ever 3 minutes. When I was awake it was like I had pseudo Tourettes Syndrome, stomping around angrily yelling cusswords out of the corner of my mouth. I had hidden some cigarettes away in a cupboard in the kitchen in case the cravings became too bad. Instead of just opening the cupboard to get at them I actually ripped it off the wall. That's right, I still had uncontrollable nicotine cravings, but now I was ANGRY about it!
Oh, but these are perfectly acceptable side effects - if you don't experience the same thing I'm SURE they're perfectly safe for EVERYBODY. I just love modern pharmacology.