Hi Laura,
My doctor prescribed me chantix two different times when I voiced my interest in quitting smoking. I wanted to try what was toted as the "miracle drug" for quitting smoking by quite a few people I knew. The overall success rate is something like triple of that any other nicotine replacement therapy on the market. The good parts of the drug is that is does slowly take away your urge to smoke entirely. If you do take it, you will notice that your cigarettes taste worse and worse as the days progress. When I tried it the first time the most trouble I had was something I call the devil and angel effect. While I still wanted to smoke badly, each and every cigarette made me nauseous and tasted horrible. It was like my own mind was tormenting me.
Now to the depression factor... I too suffer from depression and have so for more than a decade. As of now I am on medicine and have been diagnosed as rapid cycling bipolar. I think that even if your Dr does not feel any apprehension about prescribing the Chantix to you, you should really watch yourself. Both times I took this medicine I had serious side effect. The first sign I noticed where night terrors which slowly became so bad that I was soon afraid to sleep...something that was new to me entirely! That in itself made for a horrible start to each and every day. The next sign was a severe hike in irratability. Now I realize that quitting smoking will do the same, but make sure you are aware of the difference between irritation and rage. Even the slightest things sent me spinning. I yelled at coworkers for talking. I screamed at my dog for greeting me when I got home. I ruined my phone and ipod when I threw them b/c their batteries ran low. There were other types of mood swings, but my friends, family and I noticed the rage factor the most. I tried increasing my depression medicine dosage and lowering the recommended Chantix but I think it just builds up in your system enough to cause the same effects. I'd say just be aware of your own levels of depression and irritation. If your dreams worsen or you seem to have anger fits more and more it may not be for you.
Good luck!!!