I really think that quitting smoking, whether via PVs or not, is just about whether you are really ready and willing to give up the analogs. I smoked for 20 years and "quit" a dozen times, but I never really wanted to and never succeeded. However, it had gotten to the point where, since my most recent "quit", I was hiding my smoking from my wife and kids (and everyone who knew my wife and kids), which meant only smoking at work, late at night when I was the only one up at home (and even then hiding in the garage) or ducking away from the family on an "errand" to sneak one somewhere. It was pretty miserable and I obviously felt like a Grade-A a$$h0l3 for all the secrecy and lying.
When I got my first gas-station e-cig, it was like a bolt of lightening. Here was something I could use in my car, at home, or anywhere else. I wasn't going to have to douse myself in Febreeze or munch on Altoids before getting home from work. I wasn't going to have to hide packs in my car or around the house. The e-cig wasn't really as good as my analogs, but it was something, and the positives definitely outweighed the negatives. I haven't had an analog since trying vaping for the first time (3 weeks).
For me, it wasn't that vaping really replaced smoking. It was like I had to quit smoking anyway, and I was lucky to find such a great alternative. I still had cravings, withdrawal, etc., but it was a lot easier having a PV at my side. I rarely think about analogs anymore, and when I do, hitting the PV for a few draws sends those thoughts away quickly.