In general, weed is one of the more benign drugs relative to all the other popular psychoactive drugs out there (the popular drugs in human history being alcohol, weed, opiates, cocaine, and a few select hallucinigians). It has anywhere from mildly to not physically addictive, has no potential for overdose, and doesn't tend to produce extreme psychoactive effects when consumed in moderate amounts (much like booze).
That being said, it is a drug, and it carries most of the negative effects that almost every other drug has. It can be extremely psychologically addicting (which to me means addiction, though there is the bonus of your body not nearly ceasing to function if you don't have any), there is a certain negative health benefit to smoking it (though with the higher potency strains, less needs to be smoked), and since it produces a psychoactive effect it is not a good idea to operate any sort of heavy machinery or do anything you wouldn't want a sober mind to do. While I don't think pot impairs driving to the point of alcohol use does, due to alcohol being a central nervous central depressant which actively affects coordination, I'm no fan of driving under the influence of it or being in a car with people who have, though admittedly I did both a ton as a teenager and in my early 20s. Now I have a house that's my own and don't need to drive anywhere to escape parents and the like.
Full disclosure, I do consume weed on a fairly regular basis (I tend to hesitate to admit it since taking about its use is more or less a no no around here, and I don't feel like giving idiots ammo in debates when they can't think of anything more original to come up with or as a snide little comment when I make a typo or whatever). I don't drink, but like most people I need my vice in life to keep me sane or to self medicate my anxiety/depression issues or whatever (being a Colts and a Jazz fan depression is rampant here). I have a medical card in this state, and fully admit that the card is more or less a farce to be legal. And since the War on Drugs and pot being illegal in the first place is a ridiculous farce I have no problems saying that I'm going thru a legal loophole and would encourage anyone to do the same if that's their wish. We've had these cards and the stores that sell pot in Denver for 3 or so years now, and the sky has not fallen here. Crime has not skyrocketed, or even increased at all. I do not consume it to a ridiculous point, and frankly, I doubt any of you would be able to tell if I had or hadn't if you'd ever met me. In general it's something I use after work when I'm not busy with anything else, much like how most people have a beer or two after work.
And on a final note, think of how ridiculous it is to ban the growing of a plant. We don't ban poisonous plants in this country. We don't even ban plants that are the precursor to biological weapons. Yet this country has banned a plant that is non-lethal, to the point where you can't even grow an extremely low potency version of it (hemp) to produce rope or clothing. It's not only banned but it's a felony in most states. Yes, growing a plant is the equivalent to assault in most states, and in some states a worse class of felony. The logic alone is absurd. I'm obviously biased, but if I had the choice of someone kicking the crap out of me vs. someone growing plants next to me, even bad scary plants like pot and opium and hallucinogenic mushrooms (yes, I know, they're technically a fungus) I'd rather be next to the person growing plants. Yet legally they are punished worse than the violent person in most states.