My teeth are brighter, my sense of taste is a million times better, I don't get heartburn any more and I'm almost nicotine free now.
But the really big win is I can breathe, which means I can exercise... I still don't run but I walk five miles a day and I cycle at least a hundred miles a week... no way I could have done that when I was smoking, even running (OK, waddling as quickly as possible) for the bus nearly killed me. Ten seconds of effort followed by ten minutes of wheezing and coughing and wishing I was dead. The upshot is, quitting the fags enabled me to get fit... I lost 30kg in the first year and I've lost another 15kg in the following two years. I am now in the best shape of my life and fitter than I was when I was half my present age.