The one negative physical affect that every smoker must accept is the affect smoking has on one's lungs. Interestingly there has never been a case of emphysema in a person who smoked only marijuana. There have even been studies where scientist have found that THC in the lungs combats the affect of pollution. Well then, what is the negative affect?
When you smoke marijuana out of a pipe or a bong or anything in which you burn the actual marijuana, by lighting it on fire. You end up not just inhaling THC. You are also inhaling the by product of the burnt plant. Smoke is loaded with carcinogens plus the THC. Vaporizers save you from the smoke.
What a vaporizer does is heat your bud to a high enough temperature for it to release the active ingredients without allowing the plant to burn. Then it all enters your lungs in a cloud of water vapor, which is harmless. It's like breathing the air in a sauna. This saves your lungs from the damaging affects of carcinogenic smoke. Not only do vaporizers save you from substances with the potential to cause cancer, but from other trace substances such as metals which can cause decrease health.
If you're still not sold on the value of vaporizers, you have to consider they're most exciting feature (as if improved health isn't exciting). When using a vaporizer you are more efficiently removing the active chemicals from your weed. That means vaporizers equal a higher you. It's true. Make sure to grind up your bud to allow the vapor to fully access it and you'll find you get a stronger high with less weed.
What more could you ask for.