I concur, it is not for the orgasm itself. I tried it once while getting head... had to continue getting head for another few minutes after the nitrous wore off, though I was more than ready when I originally inhaled it.
I think people use it more for intensity, confusion. Some people are a little freaky.
When I tried it without trying to line it up with the nut, glorious! I suggest it to anyone. Get her/him on top and try to lose yourself in it as much as you can, then when you are buzzing all over and foaming at the mouth, take a BIG hit of nitrous. This is a special experience on par with the loss of virginity. Again, I suggest this to anyone. Once you come down, it's her/his turn! You can go back and forth like this for hours. I had a girlfriend with spinal injuries, she explained to me once we first had sex that she was concerned that she would never have an orgasm or know what it is like. This nitrous technique left her violently thrusting in the foetal position with a look in her eyes I have never seen from anyone else. She said she loved it, it was her first and that at first it scared her, she thought something very different is happening (she has had a seizure before)
Again... Nitrous=good fun!