Pro: Everywhere it's legal has seen a drastic reduction in the amount of violent drug-related crime, lower incarceration rates for non-violent offenders, and less abuse of prescription painkillers. Plus an incredible rise in quality when pot is regulated.
Con: Your straight edge friends who've never touched a joint in their lives start smoking regularly, since it's legal. Your 30+ year old friends will start talking like junior highschoolers who just smoked oregano for the first time and think they're high.
I tried it first when I was 30+, and tried it a few times at parties. Got a good laugh once and then a weird trip once... All other times were just meh, and since I never smoked anything, my throat hurt. The result was, that I stopped and then convinced my friends to stop it as well
I think it's much easier to handle when you are an adult.
So, additional plus - when it's legal, it's easier to restrict access for a certain age group (let's make it at least 21+. I heard it's particularly dangerous for teens)
I love that since it's become legal where I live I don't really have to maintain any shady contacts with lazy guys who always say they're on their way.
I just swing by the shop on the way home and pick up whatever I want with access to 10x the variety and quality of product. I love it and I'm happy it's working so well everywhere it's tried.
Yeah, straight edge people still don't drink or smoke cigarettes, even though they're legal. I doubt anything would change regarding the straight edge crowd.