The answer is yes. Why? First because, it is legal to smoke an electronic cigarette in the same places where the traditional snuff is prohibited. Second, the vapor of the electronic cigarette is not harmful to others, since it does not contain harmful particles that can be inhaled by other people around you. Also the smell is not unpleasant and the vapor dilutes in the atmosphere very quickly, so you should not bother anyone. Another advantage for the use in public places is that electronic cigarette vapor contains particles that adhere to the skin or clothing, avoiding unpleasant odors indoors after sharing with fumadores.
However there are some nuances to consider special situations.
Such as the electronic cigarette smoking on an airplane.
A priori it is NOT illegal to smoke inside a plane, however, inside the cockpit of an aircraft it is very possible for other smokers to travel with you, who can see the steam out of the area of your seat and not see clearly what you are smoking, and so to generate confusion and unwanted situations.
Thus, an airline may deny your right to smoke, claiming an alleged commitment to safety in flight, creating conflicting situations and provoke traditional snuff smokers over the course of the trip.
It is preferable to avoid smoking during the flight, but if you feel the urge to smoke at some point, it is desirable to inform any of the members of the crew that you are going to use your electronic cigarette, possibly within the basin or any part of the aircraft that is not explicitly visible for the rest of our community. Usually the stewardesses or flight attendants do not oppose you to smoke your Electronic Cigarette.
In a special case of anxiety, you can also give a few puffs and eject the “steam” to your feet, as the smoke disappears quickly without leaving odors or other evidence.