It is my personal experience that smoking does infact cause your physical health to drop. It destroys your lungs. They rot away. I feel enourmous differences now that I quit for good instead of smoking only at parties and stuff. I feel alot healthier now.
I think it does make an impact on your body. That's one of the reasons I quit. I don't want to pay tobacco companies to put poison in me. I'll leave that to manufacturers of alcohol. Oh and to almost every source of food I put in my body...