I quit smoking on Chantix though I have tried to do cold turkey on two occasions, but of no use. I have smoked for around 5 yrs with pack a day. Thanks to chantix and the support my family provided me. It really helped me to get over my nicotine addiction and I don’t feel craving anymore. You can have all the information on chantix here
http://www.chantixhome.com/ There is one thing which I would like to share and which helped me a lot initially, try having a glass of water when you feel craving the most. It a tough road but it's worth so best luck to all those who want to give up smoking.