Well, I used to love to smoke up until I was about 19 (I'm 24 now). I had a really bad experience for the first time when I was eighteen, where the weed (which might have been laced with PCP) through me into a really paranoid, out of body state, where I felt as if I was watching myself frm another perspective, and also deeply analyzing my character in a very negative way. The effects of this experience stayed with me for a while, I would even go so far as to say it was possibly life changing.
For the next year I continued to smoke, but I started experiencing brutal panic attacks where I'd think I was having a panic attack, and Id offten have to run into a bathroom and hold my arm under hot water for hours (for some reason this comforted me). The final blow came when I was smoking with some people that were just not cool, looking back, and for some reason one of them began to target me pretty viciously about my looks and personality. I'm kind of an introverted person (and even more so when I smoke), so this really fucked with my head. By that time I had started using heroin as well, so I just gave up on THC for almost three years.
Then last year I went through a brief period where I smoked. The first time I did it I was really fucked up on GBL, and my friend gave me a hit of really good herb from a pipe. I got so insanely high, as if I had never smoked in my life (tunnel vision etc..), and it really freaked me out. However I continued to smoke occasionally (I was trying last year to stop my IV drug use, so I was sticking to occasional Xanax, E, alchohol and occasional marijuana). I actually for the first time did have some pleasant experiences, but I would always wind up at some point in a very self-conscious and dark place. I also find that THC gives me a strange restlessness (perhaps that's because I also take buprenorphine), so I found it very hard to sleep.
Overall, I believe marijuana has a lot of good and fun potential, but I currently do not have enough mastery over my emotions or my mind to have a good time with it. It also has a lot to do with who you smoke with, and usually it's been around my close group of friends who can get kind of aggressive, as weed doesn't seem to effect them like it does for me-making me the odd man out.
Oddly enough though, psychedelic's like mushrooms, LSD and even DMT have NEVER given me a problem, and Ive always had pretty pleasant experiences with them. I would love it if weed could calm me down, and bring me some kind of peace, and I'm so envious of those who seem to get a lot out of it. In the future (when I'm not getting tox screened) I may give it another go. I know I can't keep sticking needles in my arm, it's just not healthy in a physical, mental or spiritual sense.