Myself and my wife have both switched to e-cigs full time - myself for 6 months, her a bit more reluctantly and recently. The tobacco analog flavours are pretty nasty, but then I neve actually liked the taste of tobacco anyway - it's the act of smoking and nicotine itself I'm addicted to. Now she smokes a menthol mix, and I'm a fan of fruit flavours.
I've tried to quit many, many times during a 23 year cigarette habit. Patches, gum, straight cold turkey, Allan Carr, you name it, I probably tried it. Longest time was a year before stress got me smoking again. The day I had an e-cig, I've not had a single tobacco cig since. My phlegmy cough is gone, my sense of taste is much better, I don't reek of smoke (going back and smelling an old coat that I wore while smoking just smells rank - when you smoke, you don't realise HOW stinky you are to non smokers). I also feel better.
Nicotine itself is highly addictive, but in stimulant terms isn't much different to caffeine. It's the tar, carbon monoxide, benzene and all the other carcinogens as byproducts of combustion that are really terrible for your health.
We're still on the hunt for the perfect clearomizer that gives the right combination of warmth, vapour quantity and reliability (some tanks crack very easily), but generally it's been a very easy transition for me. My wife struggled at first as the amount of vapour wasn't enough for her in comparison, but a dual-coil seems to have fixed that, and we hand-mix the liquid as we both prefer a different mix of PG to VG. I am slowly tapering my nicotine mix down (currently at 8%, which is already pretty low). I'm still hoping to quit outright at some point.
Are they 100% safe? Don't know. Most studies have shown no risk, and the worst impact has been some inflammation in those with existing breathing conditions. Given the components of the liquid are all individually safe for consumption in other products, as long as you get it from a reliable supplier that doesn't use cheap chinese contaminated liquid, it should be pretty safe. It's certainly a lot safer than the known highly dangerous tobacco cigs. I'd have no problem with goverments ensuring product purity by regulation and enforcing age restrictions - all the sellers I know insist on 18+ only, and are entirely upfront about the dangers of nicotine.
Yet European legislation is lining up to class them as medicines, and defacto ban e-cigs, as they obviously don't have a health benefit in and of themselves - only in relation to the alternative. It seems ludicrous to try and ban a product that is at worst far less dangerous than cigarettes, when cigarettes themselves don't have to clear the same proposed hurdles.