Marijuana was legalized in my state. I've never touched it myself but I was actually in favor of this and voted for it because I believed (and still do) that the war on drugs was a giant fleecing of the American people. Since then, what has happened here is that we basically got the worst parts of everything.
1. Since "hey, it's legal now," lots of people take that to mean they can smoke it wherever and whenever they want. While driving, in parks, near schools, immediately before class, and so on. Along with legalization, there should have been laws enacted, communicated, and enforced which would encourage people to get stoned at home in their own time instead of out in public where they are a danger or at least nuisance to everyone.
2. A good majority of the billboards in my state, in cities and along highways, are now for MJ retailers. I'm worried about the impact this persistent advertising has on normalizing the casual use of psychoactive substances for children who see these ads constantly in their day-to-day lives.
3. The retailers are regulated and taxed, but their prices are quite outside the range of those on a lower to lower-middle class income. As a result, there is still a lot of gray-market dealing going on to provide lower prices for those that accept the risk/inconvenience. And therefore with it, some amount of crime. So legalizing MJ did _not_ suddenly make everything above-board and peachy overnight like all of the legalization supporters had claimed it would.
I don't know that I have a solution for any of this. I only hope that right now we are just seeing some kind of peak the way cigarettes were positively mainstream in the 70's and then gradually faded over the new few decades as society realized what they were doing to us and our children over the long term.