Most well-adjusted people that smoke weed have pretty normal, relaxing experiences from what I've seen and heard from friends. I know that for some it can actually have very positive effects as well, especially for people who have difficulty focusing, socializing, or a variety of other daily parts of life. I also know that others can have poor experiences that involve paranoia and sometimes fear. My personal belief, having seen many different types of reactions first hand, is that weed is no different from any other herbal supplement, medication, or even food: it hits everyone differently.
I can't stand stupidity and the fact that weed renders quite a few people relatively stupid or at least makes them think it's cool to act that way pisses me off. I blame the person, though. Shitty, stupid people aren't going to magically change because they inhale a bit. The flip side is also true though and I've known more than a few Dean's List students that swear the only reason they do as well as they do is by partaking regularly.
Fact is, marijuana is becoming legalized in some places and nearly every state has legislation at varying degrees of completion somewhere in the pipeline. Sooner or later it'll be no different than cigarettes or alcohol. Stoners will then be no different than smokers or drinkers and they will be judged by society based on their maturity and accepted or shunned accordingly. If they act like most smokers and drinkers do now and avoid being obnoxious douchebags about it in public, people will accept it. Most people I know wouldn't dream of smoking too close to me, just like most smokers keep to specific areas in public and don't go blowing it in peoples' faces as they pass by.
The next five years or so will be very interesting.