I don't really understand them. For one thing, why are they 'electronic', and secondly, what are people actually in- (and ex-) haling, if you please? Another type of smoke? Steam? Moondust? Some other strange brew? Yes, I know I could look it up, but then again so can you, and I prefer speculating.
This boutique isn't the first I've seen in Paris so it looks like it's a bit of booming business at the moment. And if it reduces people's cravings and / or consumption it must be a good thing.
Although probably like artificial sweetenters they'll find out soon that electronic cigarettes are even worse for you than the real thing, you mark my words.
And why not...