I used to think that making a woman cum from oral sex was the ultimate high, but using the above technique is an absolute feeling of power. NOt only is there the huge ego boost of making your mate cum REALLY hard, but once that orgasm hits you are in complete control (at least with my wife). There's the feeling of having the power to make her lose control and experience a pleasure so intense that she could not fight it if she wanted to. I'll admit it, I love that.
Now my wife is one of those lucky women who has a really easy time achieving orgasm so all women may not respond as strongly. That's what I hear though, and it jibes with my experiences.
Guys let me tell you, the g-spot can be hard to find, but it's worth the hunt!