I think it depends how you do it. Some people seem to have the idea that because it's not cigarette smoke, it's ok to 'share' it with anyone else around! I think people who are vaping should remember that their 'steam' could also cause problems and try to be as careful of it as they would of smoke. Most people I know are very considerate and definitely not anti-social, but I know one woman who blew a cloud of steam right in my face - it actually caused me some breathing problems though I'm not sure if this was due to the steam or the chemicals in it. She was quite put out when I asked her to be more careful in future. I've also had to ask another friend not to 'vape' in the car when I am giving her a lift, for the same reason. She would never dream of lighting up when I gave her a lift in the past, but got out her pipe without even asking me!
It would be a shame to discourage vaping as so many people find it helpful in giving up smoking, but I hope that soon a 'vaping etiquette' will form, so that the rest of us won't have to keep choking on clouds of steam!