My friend doesn't weigh a whole lot, and he can get extremely noticeable psychedelic effects from doses that only make his friends stoned. Part of that is the low body weight, and part of it is that he doesn't smoke too often, whereas some of the friends smoke every day. For social smoking, he's learned to take half hits by diluting the smoke with regular air, which prevents him from getting too high to interact with people and also makes it easier on the vocal cords -- important since he's a singer.
While he doesn't tend to have particularly spiritual experiences with cannabis (except for some potentiation of a negative spiritual experience he was already having from powerful meditation), he does have pretty amazing experiences with music. When he's at a psychedelic dose of cannabis, where the visual framerate shows itself with open eyes and closed eyes present some visuals that aren't too intrusive, songs can create entire worlds that he can be immersed in. Not in the sense of hyperspace -- it's very different from that. If not always less visual, then definitely much less spatially rich. But the sound, the emotions, and the imagination all form a very immersive experience which is based on the foundation of a song's overall character. He says that every song has a somewhat synesthetic character to it even when he's sober. This character includes some mild visual elements when eyes are closed, some emotional and intellectual elements, and a mental sensation that can't really be described in terms of emotion, thought, or the five senses. When he gets high, the song's character takes over his experience completely.
To quote Morinth from Mass Effect 2, talking about a band that creates experiences like that, "They're amazing. They get totally inside my head and tear it to shreds." This is definitely said with a smile.
However, if he gets too high, around the point where CEV's become intrusive enough that they can't possibly be ignored, then it always stops being fun. Misery sets in and not even the most upbeat music can dispel it. At that point, he takes some Benadryl and melatonin to go to sleep quickly. Unfortunately, the thirty minutes that it takes for the medicine to kick in feels like so much longer, and it's always rather tormented. It's weird. Cannabis makes him feel nice at low doses, neutral at medium doses, amazing at high doses, and horrible at very high doses.
