Smoking is a weird issue in the American Church right now. Per the public school system and public opinion in general, smoking is the only mortal sin. In reality it isn't a moral issue if it is in moderation, but the same anti-smoking attitude is pervasive in the Church. I know priests who teach at seminary, who are very adamant about not smoking, but as they admit, this is not for moral reasons but to preserve simplicity and poverty as priests. Though they advocate the same for laity. At the same time, you have the traditionalists (laity and clergy) who seem to pick up smoking simply because it is ok, what was done back in the day, and to stick it to those anti-smoking novus ordo people. This is also incredibly stupid.
I would say that smoking is a vice, but a minor one. Certainly we should not put poisons into our bodies, as that would not please God. However, every particular instance of smoking is not that damaging, just as every particular instance of overeating is not that damaging. However, just as over eating is gluttonous, I would suspect that smoking so that one is addicted is equally a bad thing.