Well I've done my own "experiments" for 10 years
It hasn't been a gateway drug for me, I haven't got addicted and from my own experience I've seen many others like myself who can use marijuana in moderation.
Most of those points made in the previous post are pretty much bogus. Yes marijuana isn't healthy when it's smoked, usually due to the burning leaf material, rather than the drug itself. Besides that, I always compare it to the legal drug alcohol and wonder, "if marijuana is illegal, then why is alcohol legal?" Noone who advocates keeping marijuana illegal can trully answer that because marijuana is much less harmful than alcohol, yet it's illegal. Alcohol kills hundreds of thousands every year in North America alone. Cigarettes have been linked to almost a quarter of a million deaths a year. Yet you'd be hard pressed to find any deaths linked to marijuana. Oh right, some have allergic reactions. Well some people have allergic reactions to strawberries.... LET'S BAN THEM TOO!
As for being addictive, no marijuana is not addictive. If it was, then I'd be addicted long ago, yet I find no overwhelming urge to smoke a joint. I'm sure it's possible to get addicted, but it's possible to get addicted to anything, for that matter.
Final conclusion is that marijuana is a wonderful drug, it's a great alternative to alcohol and I definitely recommend trying it out. Just avoid harder drugs, like cocaine/crack, heroin, meth etc. unless you want to be on street corners sucking cock for those drugs. Marijuana though, you'll never lose control over. That being said, try to be responsible with it though. Doing anything excessively is not a good thing. Best times are on the weekends and holidays, not during the week, during school, college or while you're at work.