I took it, worked for a couple of months but then I started smoking again. The stuff does work, but it requires discipline on your part to stay off cigarettes. It kills the craving, but not the habit - the habit is all on you to quit.
As for side effects, don't buy into all the fear mongering without giving it a go. It's really not that bad. The biggest issue for me was some bad stomach cramps, but I found that you can get around this by always taking the pill on a full stomach after you eat, not before...