Glorious movie with so many cool effects and camera techniques (I'm not talking about the 'trippy' sequences; those are indeed a bit dated but not harmful to the enjoyment of the film). Like others pointed out, this is the genuine article. You can't act out these ideas, at least not at that time you couldn't unless you believed in them. That makes this movie precious and genuine.
I go through all hippie movies from the era and most of them are pretty horrendous. Thankfully my quest is not in vain. Check this one out man, you'll love it.