Yes, it's true. If she has really developed the muscles, and the technique, it is an incredible experience for the guy - and impossible to avoid coming.

Perhaps the most intense orgasm I ever had was the first time I was in a "milking pussy". We had been coupled for a while - she was on top - she kissed me very lightly, then moved her head back to look at my face and said, "You're going to come now.". Her first contraction caught me by surprise; the second brought me to the point-of-no-return; and I convulsed on the third.

Afterwards she asked "Is that the first time you had it pulled out of you like that?". I agrred. She went on, "I could tell. Most guys try to fight it when they know what's going to happen. They can't avoid it, but sometimes ruin their climax trying. I would have held you on the edge longer if I knew it was your first time."