I consume marijuana regularly and enjoy it. Of course living in California, it is very easy to find, relatively cheap (I spend way less on weed every month than what most of my friends spend on Starbucks), and legal.

I had never tried it before moving to California (I come from a European country that vilifies all these things, and until I was an adult I thought it was some weird evil substance that turned anyone who tried it into a zombie), and then realized that I enjoyed the experience. If I were in a country where it is illegal, I'd be fine, but I'd definitely miss it (the same way I'd miss tea or chocolate).

Additionally, I have anxiety/depression/social issues that are greatly helped by THC. For example, I am extremely introverted, and tend to live in my head/on my computer all the time. Smoking a bit opens me up and makes me very talkative, which has been very helpful in social situations/relationships many, many times. Besides making me very talkative and much more upbeat and excited than I usually am, friends have told me that my behavior is not noticeably different while influenced by marijuana (i.e., my ideas are still coherent, I can still reason logically and rigorously, etc.). These friends have always been very straightforward and honest with me, so I trust them to not sugarcoat things for me. (to reinforce this, some of my most upvoted comments on Hacker News were written while high!)

I relate a lot to this essay by Carl Sagan in which he describes his relationship with the substance: http://marijuana-uses.com/mr-x/ . I find marijuana very helpful when doing certain kinds of intellectual or creative work. For instance, it's not that helpful when learning new things, but it is very helpful when going over ideas and concepts that I am already familiar with. It is helpful in 2 main ways: 1) linking ideas together that I had not linked together before, and 2) visualizing things better (especially in mathematics/physics). Re-reading a book or paper that I have already read, while high, is almost always sure to yield new understanding or ideas for me. It has also happened that I'd struggle with a musical piece (eg. on the piano or guitar) and that it all "crystallized" once high. Maybe this phenomenon is similar to why some people can pronounce foreign languages better when drunk. I do retain the insights and advancements when sober, and take notes in a notebook (which are coherent and hold up to scrutiny the next day). The one disappointment has been with programming: at best I program as well high as I do sober, and at worst it does slow me down a bit, without making my code any better.

I have been meaning to make more "formal" experiments on myself while high vs sober, e.g. on learning tasks etc. (I did do various tasks on the Nintendo DS game "Brain Training", and noticed no difference in my results while high vs while sober).

(I'm obviously always sober during work hours etc. - what I described above I only do on my free time, ie. weekends or evenings, while working on personal projects/research)

All in all, I think you get out of weed what you "put into it". Smoking weed doesn't turn burnouts into math geniuses, and vice versa. It needs to be an addition to your lifestyle rather than your whole lifestyle. I certainly don't think marijuana is a magical substance that makes you smarter or anything. I do believe that it puts your brain in a state in which it usually is not, and that this can be constructive for reasoning (the same way that talking to someone you've never talked to before, or talking to yourself (see rubber ducking) can help reasoning). All that being said, it is obviously not the case for everyone. For example, my girlfriend does not experience all of what I just described - for her, smoking weed just makes her more relaxed and happy. I'm sure there are many, many variables at play; but I'd still encourage everyone to give it a few tries (the first few times being not representative of the experience in general because it's all new to you) to see what it does for them.

Finally, I really like this essay by Sam Harris: http://www.samharris.org/blog/item/drugs-and-the-meaning-of-...