I've been on ViP electrics for 7 months now, not sure if I've saved the small fortune that I thought I would though. Have to say they aren't as great tasting as perhaps i wanted them to be, but definitely worth it if you want to quit regular cigs as these are not proven to be harmful, yet.
I find myself puffing a lot more as its easier, especially at work sitting at my desk. A cartomiser which is advertised to be equivelent of 40 fags lasts me 2 days when a regular pack of 20 real smokes lasted me 4 days (i used to smoke strictly 5 a day), now its pretty much puff when you like, and sometimes you forget to stop as theres not butt to burn to!
The battery end needs replacing every 4-8 weeks despite being advertised to last 3 months as well - this is the most expensice bit, you have to pay £5 delivery with each order so its better to buk buy.. I'd say all in all its costing me roughly £30/month when i was paying about £45 for regular smokes