Quite frequently from my mid teens to early 20's, although it was not my drug of choice. It was pleasant more often than not initially. Later on, I didn't have bad trips either, but some unpleasant ones. And I recall quite often by the end of the trip, I was just wanting it to end already so I could sleep.
It did open some doors of perception for me, made me view reality differently. Almost disturbingly at times. Coming down off high on LSD in Sunday school for example, around 15 years of age I'd guess. Gave me a different view of things .. lol.
Overall, I believe the experience was positive. But after taking it a half dozen times, I should have stopped.