I've had next to no direct experience with narcotics. I've read some about it, and seen the effects on others (many times tragic). I'm familiar with the Opium Wars and the effects of heroin on China under British rule.

There was a book title some years back which rambled for a long sentence to the effect that the problem with smack was that it was so hard to quit and then once you did the worse thing was that it felt do damned good when you did use it again.

An earlier title pretty much sums it up: "It's so good, don't even try it once".