Ill tell you about my experience.
Me and a few friends bored as hell (like usual), had no bud left, and someone mentioned salvia. Only 1 of us 5 had tried it before and not much effects.
So we leave to the headshop and pick up a thing of salvia x40. Get home, load a bowl and I go first, biggest hit and longest held in. All of a sudden, my head goes WOOSH and I start laughing immediately while my friends pass the pipe. Suddenly my world transformed and I was riding a T-rex's back constantly trying not to fall and climb to the top of its head. After about a minute I fall on my back (Apparently I was rocking my chair back and forth). I get up and wander around. I see a picture on the wall and a lady doing dishes. I want to go talk to her right? So I see my friends doggy door thinking it was the only way in since the door was locked so I was trying to get in there for the rest of my trip =P (not quite small enuf for the doggy door)
All in all, it was too out of control for me and have never done it sense (save 1 time with lower strength x20) although it was the most visual trip ive ever had +5 on the visuals =)
I say its worth buying for the experience at least once and go from there on whether or not u want more...
GL with it man, you guys will trip! Get some 40x btw 20x is good but nothing compared to 40x