Well, I, as a natural flat (one plane) swinger, decided to check this book out. I decided after reading it to really focus on one thing, which is to keep my left arm (I'm a righty) pressed to my chest on the downswing.
The results have been phenominal:
4 300+ yard drives in the last 2-3 weeks (the first of my career that I can remember)
A 280 yard 3 wood off the deck (had 264 to the pin and rolled it through the back of the green)
1 full club increase in distance with my irons
Yesterday, I reached the 198-yard par 3 17th at my home course with a 5-iron (and my lofts are week - this is the equivilant of most sets' 6 iron)... I sank the put, too, to birdie the hole for the FIRST TIME!!!
And... yesterday, on the 548 yard par 5 12th, I had approx. 240 left from the center of the fairway and a 3 wood or a 25* 5 hybrid (which plays as a 4-iron for me); I knew the 3 would be way too much and the 5 hybrid way too little, but I figured I'd lay it up short and try and get up-and-down. So I layed into the 5 hybrid... and found it pin high, left of the green. That's 240 yards with a 25* hybrid.
Here's the kicker - it doesn't feel like I'm swinging at all. It's just nice and easy, focusing on keeping that left arm strapped to my chest, and the results have been wonderful.
I'd recommend the book.