My wife started vaping at the beginning of the year and for someone who couldn't go without a dirty stinking cig its worked out quite well.
She has gone from a 20 a day habit to £30pm on e-cigarettes. Even the smell of a fag makes her feel ill now.
The question is cartridge or refillable tank?
She buys hers from smokers angel (
http://www.thesmokersangel.co.uk ) as a disposable cartridge, makes it slightly more expensive but it's easy, unscrew the old one screw in the new one, job done.
They really are a great way to help people stop smoking.