They didn't bother me too much tbh, as the smell of them isn't as offensive. The long-term effects of smoking are well known to everyone though.
The long-term effects of vaping, are not.
I find that revolting sickly-sweet smell of vaping utterly offensive. Its vile.
As for how "harmless" it is - its not been around long enough to judge the long-term effects - yet. But I would safely assume that actively inhaling a pungent, sweetly flavoured nicotine-based chemical into your...