I have no problems with people smoking ganja or anything else for that matter, its' your body, do with it as you will. In a truly free country, you would be free to do it without worry of being arrested for a, truly victimless, act.
As to the effects of marijuana, I'm prone to think that the effects on health by cigarette smoking is more due to the 250 chemicals added to the manufacturing process as required by government regulations to lower tar and nicotine are more at fault than just smoking the tobacco product would have if it was pure tobacco.
There is also more and more evidence to support the claims of positive medical benefits to smoking ganja.
If your going to "medicate" for whatever reason, I have more faith in the all natural stuff (ganja) than the marketed chemicals that doctors will give you.