Mostly harmless. Legalize it, regulate it, promote responsible use just like other legal drugs, and watch it cost society less.
I actually knew a person whose life had been improved by marijuana. He used to have problems with rage and aggression. When I knew him the chronic had turned him into a calm and productive (if unambitious) person.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.