I think criminalizing it is a massive waste of money, and literally ruins lives.
That said, if legalising it stops all these drug smuggling problems, then so be it. I'm sure there's got to some negative points to it's legalisation though, unless if it's just been illegal for the past several years for the heck of it.
Some would argue that if it were legal, drug dealers would start pushing harder drugs. Others say that it'd wipe out most of the black market for all drugs. I think it's conceivable that you'd see a bit of both.
Ideally I'd like to see it packaged, taxed, regulated and sold with appropriate warnings clearly communicated.
People are very quick to say 'prohibition doesn't work', but it's clearly a mistake to abandon all efforts to reduce smoking and alcohol abuse.