Well, I don't claim it's harmless. I was just dubious of "it's just as bad as cigarettes" since by all accounts this is emphatically not true.
Frankly, I haven't seen reliable studies either way. Look at it this way: much like using a bong, vaporized material is far easier to inhale than smoked material. I've seen people suck in massive amounts of cloud-like vapor in a way that I've seen few cigarette smokers. That shit can't be good for you, and is definitely not harmless.
Personally, vaping is actually harder for me to stomach. That glycerine makes my lungs feel like they've been caked in asphalt after a couple of minutes, something that I simply don't get from cigarettes. Given that cigarettes have this huge stigma, I smoke socially and on occasion; however, whereas vaping is found more acceptable due to the lack of an unpleasant aroma (no matter how pungent) vapers are doing it far more they would normally smoke.
Smoking cigarettes. Smoking weed. Inhaling vapor. It's all probably a bad thing, and the delivery of more nicotine seals the deal for me. That shit is downright awful to your body.
So, my argument is anecdotal, and should be given the same weight.
But, as @Thenomain said, vapers around our parts are downright asses about that shit, and need to be given a fucking steel-toed colonoscopy more often than not.