Depends what you define as long-term. Hon Lik invented them in 2003 and vaping has been a mainstream activity since 2009 in the UK. During that time there's not been one documented incident of a vape-related illness. Not one. OK, there have been some like the Brummie twat who attempted to blame fluid on the lungs on vaping - but soundly debunked afterwards. So what long-term illnesses? There's not going to be anything vastly new over smoking-related diseases except ones attributed to the combustion materials won't exist and others related to aldehydes and the like will be fewer by virtue of reduced levels in vapour. Clearly, the best thing to do is not to vape or smoke - but for those attempting to get off fags, vaping is a no brainer. Study after study has demonstrated that the addictive quality of nicotine is reduced when isolated from the toxic smog of fag smoke. And I can attest to this on an anecdotal level because quitting vaping was an absolute breeze. I tried cutting down, that didn't work. I tried cold turkey - no pangs, no nothing. Bonus! So, no, I've not done heated tobacco and loathe the concept. Strikes me that would be harder to quit from (evidence for this - nada), but my main objection to it is the companies producing it.