I loved smoking. 3 PAD. Never tried to quit. I liked the effect of the nicotine - a 'relaxed focus' - something that as far as I know, no other drug does. Some focus (or go beyond focus

and some relax (or go beyond relax), but none that I know of do both at the same time. I also liked the smoke - after ecigs, I think it is at least 50% of the habit. Imo, it adds to the focus - a non-distracting presence....
"Sherlock Holmes sat silent for a few minutes with his finger tips still pressed together, his legs stretched out in front of him and his gaze directed upwards to the ceiling. Then he took down from the rack the old and oily clay pipe , which was to him as a counselor, and, having it, he leaned back in his chair, with the thick blue cloud-wreaths spinning up from him, and a look of infinite languor in his face."
Holmes again, to Watson:
"It is quite a three pipe problem, and I beg that you won't speak to me for fifty minutes."
Or, we can remember the case in which Holmes needed a pound of the strongest shag tobacco to resolve the problem and stayed alone all the day smoking, and Watson found him in a sort of trance, in a room that "was so filled with the smoke that the light of the lamp upon the table was blurred by it and my first impression as I opened the door was that a fire has broken out".
When I got my first 'good' ecig - a Janty Dura-c (510) after a failed supermini, mainly out of curiosity, not trying to 'quit cigs', I decided when I got the 'urge' I'd hit the ecig first for three draws and if that didn't work, I'd have a cigarette. When the nic hit the blood stream, I was good. And never had a cigarette after that. The nicotine and the vapor was enough to satisfy. I don't claim that to be true for everyone, it quite obviously is not. I've never had any real desire to use WTA and I know that for some that 'does it'. I don't need big clouds, just some clouds (which is what the supermini didn't provide that the 510 did.)
And, again, while not an intended goal, I had good "collateral undamage" along the lines that billh speaks - lighter upper respiratory effects and no morning cough which for me was usually in the winter here in Ohio.
All that said, if somehow ecigs are banned - or I run out of my 'preppers' supplies, I'd go back to smoking.