I smoked for 6 years; quit cold turkey on a whim earlier this year.

Edit: For those looking to quit, the first 3 weeks are pretty shitty, but after that not so bad. I still get the rare craving and occasional dream about smoking, but that's about it.

So far the only noticeable plus for me has been that I don't need to feel like a leper in public since for whatever reason most people are horribly offended by cigarettes these days. I was sort of hoping to develop super powers, though.