They're an interesting one in terms of 'should you use them around non-smokers', as there's no statistics on exhaled contents of nicotine (that I've seen) so it

They're an interesting one in terms of 'should you use them around non-smokers', as there's no statistics on exhaled contents of nicotine (that I've seen) so it's quite difficult to make a call in terms of second hand health risk. First hand health risk? It's your body so do what you want. There's other issues, do they smell? Yes, some do, they have flavourings in that will impart a smell. However it's quite faint in a lot of cases, it bothers my girlfriend in the car but not at home. Is it anti-social? Depends on the social group you're in, I generally hang around with smokers (maybe there's some selection bias inherent in social groupings due to the smoking ban) and a couple of us have shifted to e-cigarettes (traditional style and vape style) and no one minds. I wouldn't use one in a restaurant but I would in a pub or nightclub. Hopefully they'll avoid regulating them for a while, but there's rumblings of regulation on the horizon in the EU.