I'm gonna have to change my mind on this one. It is possible to OD on nicotine from these things, I did it on Saturday and I'm still sick as hell. So there you go.
The thing is s, you don't really know how much of the drug you're getting in your system. It's not like cigarettes which are full of tar, which you have an automatic shutoff mechanism in your head for. E cigs you can sit and puff on all day, it feels like water vapor.
The good news, though, is the thought of a cigarette or an e cig makes me want to hurl, so I'm pretty sure I've effectively kicked the habit. That's one way to do it, though not recommended. Lol.
Seriously, be careful. Nicotene overdose can be very serious and you an even die from it.