I had one as part of a full Tantric massage last year. I had a female therapist (can't help feeling a male therapist would be in it for the wrong reasons!), it was an amazing experience...quite emotional, a bit of an "out of body" experience in some ways (after she had made me climax she kept one hand pressed gently on my pubic bone and the other was in contact with my clitoris with some fingers inside me but was totally still), she kept whispering to me to use the controlled breathing technique she had taught me before the massage started and I actually felt like I was floating! I was looking down at myself on the massage table. I couldn't tell you how long I was in this trace like state, my husband had dropped me off and gone shopping to kill time while I had the massage, he returned 2 hours later just as the therapist was coming out of the room, but he claims she was chatting to him for over half anhour while i was still in there...sleeping!
It was an experience I would go for again and would recommend to anyone with "hippy" tendencies like me, but be warned...it is not cheap!