Pot hit big time in the 60s, during my high school days.

1) I've always noticed how detractors made it much worse than it really was, honestly it wasn't that powerful until the mid 70s. It remained on the narcotics list because the right-wing associated it with liberal hippiedom. Some obvious medical uses took many years to be legalized.

2) That said, I've always wondered if it was as safe as proponents claimed. First, inhaling all that unfiltered smoke CAN'T be good for a person. Observing some of my kids Gen Y crowd, there seemed a connection with a lack of ambition and burnout, but many bounced back. Was pot simply a burnt-out rebel kid's drug of choice (replacing the alcohol of years past)? It seems that alcoholics or coke-heads have it much worse, many seem to "outgrow" pot.

3) Its hard to tell about the memory effects, those like Bill Maher seem unaffected. I knew several grad students in college who were habitual smokers. The confusion was that some pot smokers were also into harder stuff (mostly coke, sometimes heroin or meth, which did affect the brain).

4) I've been expecting a lung-cancer connection, but it hasn't emerged (yet).