I bought a nicolite e-cig from WHSmith for £20, 19 days ago (you get 2 cartridges, equivalent to 40 cigarettes, and a USB charger - refills are 3 for £6.99 - equivalent of 60 cigarettes.
I used the e-cig and thought it was good.
For the first week I used 2 cartridges. Before I gave up I was smoking between 10-20 per day. (usually 10 in the week, more at weekends if I go out)
Found it fine, then week 2 started taking it to work, but leaving in my car, so i wouldn't use it, but could go and get it if things got bad enough that I felt myself about to ask someone for a smoke.
I haven't used it since Thursday now, but am going to keep taking it to work and leaving in the car, as a comfort blanket.
I've given up before but never found it this easy, the thing that I think is key, is remembering they've got nicotine in, so you will eventually need to give up the e-cig, if you don't want to stay a slave to your nicotine addiction!