I've been taking Wellbutrin for depression for close to 4 years now. On the mental health front it's definitely helped me immensely with respect to my overall quality of life. I no longer need/want to sleep 14 hours a day, I actually feel like doing activities I enjoy, etc. In short, it's really eased the symptoms of clinical depression.
As far as its effects on smoking, it was very, very drastic. Within a few weeks of starting it I found that my cravings had reduced significantly. Mind you, when I do smoke I don't get the same headrush/buzz off of cigarettes that I used to. I used to "have" to have a smoke every hour or so or I'd go absolutely mental. On Wellbutrin I could go an entire 8-hour workday smoke-free with only mild to moderate cravings.
The problem was is that I really, really enjoy smoking. Then, i discovered vaping. I started vaping 2 weeks ago and haven't had a single cigarette in that time. Pretty amazing, this is by far the longest I've gone without smoking since I started 18 years ago!
I read through this thread and I see that many people do have very negative reactions to Wellbutrin/Zyban. In fact, 2 of my friends and my mom tied Zyban and had to stop within a few days due to unbearable side effects. The only one I had was nausea, but that subsided after a few weeks...