My experience:
I find myself very "attached" to my e-cig. If I'm not actively vaping, I either have it in my teeth like a pipe (not a very feminine habit but too bad 8-o), puff on it like a pipe, in my hands or close by. I did not increase my nicotine level but used a lower nicotine level than when I was using analogs.
This way, if I want to vape my brains out, the likelyhood of getting an OD headache from the nicotine is diminished. (I'm hooked on Janty RY4 and Puresmoker's Riskee Juice. )
Mostly, my ecig has become my pacifier/crutch/nervous tic. Students of psychology can mull that over at their leisure.
All I know is that I don't smoke regular cigs anymore, I can breathe and a cold does not put me in bed for 10 days with a wracking cough and that makes me very very happy.
...back to regular programming.