Worked for me... I tried everything else in the past, wellbutrin/zyban, gum, patch, etc.. I smoked for about 15 years, and even lost my father to lung cancer, and was unable to quit.
My experience was similar to group captain mandrake's ... basically you just take it and still smoke, then you just have less and less of a desire to smoke.. the action is still there, lighting the cigarette, and inhaling, but it doesn't do anything for you.. just kinda tastes crappy.. it gives you no satisfaction... after a couple of weeks you find yourself not really smoking anymore. I took the pills for about a month... my insurance didn't cover it, so it was expensive [~100 something/mo ... which is actually far less than cigarettes, at least in NJ], but worth it. I made sure that before I stopped taking the pills I did everything I could to 'crave' a cigarette... get drunk.. eat mcdonalds... go offroading.. etc.. all the times/places where I'd usually smoke a ton.
I know of at least 2 other people locally who quit using it.
As for side effects ... my only real complaint was sleeping... it was hard to fall asleep and hard to wake up.. I *never* sleep through an alarm [unless im hungover], and while on chantix, I slept through my alarm a couple of times.