As far as the people talking about the effect they get from weed, it's worth noting that after a certain period of heavy use (I'd say a year or two of smoking every day would do it) the effect of the drug basically flips. While it earlier made you feel sleepy, lethargic, laughing at nothing, etc it can now make you feel alert, hyperactive, inspired and more 'awake' than when you are not stoned.
All of you who complain of not being able to sleep, this is a clear indicator of this change, I've got it too which is why I've looked into it. The problem with this is that your system has adjusted to having these chemicals in your system so that when you are not smoking you are experiencing depressed functioning, which can seriously enforce the addiction cycle, making you want to smoke in the morning, etc. I have been smoking heavily (every day) for more than five years now and I feel this process very acutely. I do still enjoy smoking and do enjoy the 'charged' feeling I get after my first smoke of the day (diminishing returns after that) but am not a 'weed optimist' I don't think that any drug is worth attributing things like creativity, artistic development, etc to it. I know I'll hear from some of the E, LSD and Herb evangelists on here about this but I think that the drugs are usually incidental and most good work happens in spite rather than because of them. I certainly wouldn't say that smoking herb enhances my creativity, it FEELS like it does and will get me enthusiastic about working and I'll feel that what I've done is amazing but the morning after re-appraisal often holds nasty surprises, I'd say about 50 percent of the time. Usually in the first hour or two after the first smoke of the day I get very active, inspired etc but this is inevitably followed by the long slow tapering off into stupor, compulsive eating, TV watching etc. Smoking more helps, but with definite diminishing returns. I've found often that I'll get that brilliant rush, start something and then watch it degenerate into rubbish as my buzz wears off and I no longer feel excited about it.
As far as K-Punk's article I think there are some truths in there but criticizing weed without ever having smoked is like criticizing a book you've only heard about from others, basically weak. If he wanted to make an informed critique that people who smoke would take seriously he would have to engage with his subject and try smoking Otherwise he's basically preaching to the converted and will certainly not reach people like me. I do feel that a critical discussion about herb is important though, too often people adopt the 'it's a harmless herb from the earth' attitude which I think is idiotic. Weed is a drug like any other and depending on your approach to using it can also be very damaging to life, health, sanity etc. Regarding the rasta approach to smoking, talk to a few people who live that lifestyle and you will learn that theirs is not always an uncritical attitude either, many, especially older people have health problems related to smoking but feel addicted and unable to stop. Lee Perry is also known to have taken breaks of several months from smoking because he worried about it's effect on his creativity.
The only drug I can reccomend without qualification is COFFEE! Sizzling mud of life, I don't know where I would be without you. Talk about a drug that enhances creativity, I've made way more good music on coffee than I have when smoking.