Health and Science Perception: E-Cigs: the newest leap in Science

I am sure you must have heard of the words E-mail, E-paper and heck even E-Dawn, but ever heard of E-Cigs?
People were seen loitering around in New York, with an E-Cigarette in their hand, and although they were smoking in the non-smoking zones of the area, there was hardly any puff of smoke seen. But how is this possible? How has science created such a marvelous achievement of creating a cigarette that is not the source of any sort of pollution? Simply marvelous I tell you, marvelous!
No smoke, no irritating smell of the smoke, no choking up due to the smoke, so a question definitely forms in one's mind of whether it is safe for the people around the E-Cigarette user.
The biggest advantage of this E-Cigarette is that it doesn't use the process of fire or combustion. So therefore it doesn't create any smoke and neither does it release toxins. It does however uses a battery, to create vapors of nicotine which are then directly inhaled by the user. So the users are not 'smoking' but are 'vaping' (creating vapors).
These vapors simply consist of water and propylene glycol (PEG), the same substances which are used to create theater smokes. It is still arguable however as to whether this vapor consists of other undiscovered harmful substances.
However that is not the major concern right now. Some people believe that this E-Cigarette should still be banned in the no-smoking zones, although it does not create smoke or burn tobacco.
Some scientists believe that the vapors do contain some carcinogenic material, and although E-Cigarette do appear to be clean in creating no smoke, it is still however harmful and not better than fresh, clean air.
New Jersey and Utah have banned its usage in the non-smoking zones, however in other areas people are still in a state of confusion as to whether to use it or not in non-smoking zones, since it doesn't make use of the tobacco.
  Scientists are still confused about the exact levels of nicotine and toxins that this device can emit, and are still in the progress of evaluating its effects.
I believe its best to avoid believing in such advertisements which encourage its use, and to avoid standing near these 'vaping' people, because the side effects of this device is still unknown.