I bought this book, actually I bought a copy for myself and a copy for a friend. After about 2-3 months of applying Jon's methods I measured myself (I don't own bathroom scales!) and I am confident that I had dropped a dress size. That was without ever feeling like I was on a diet or restricting my calories or fat intake in any way.
The beauty of the Gabriel Method is that you can also find alot of free materials on the website - I advise against paying to join the forum as it isn't worth it in my eyes. The forum used to be free until sometime last year, Jon started charging to access the forum so he lost alot of very faithful followers. Now, the forums are paid membership-only and not anywhere near as lively or informative as they once were.
But still, there is alot of great information to be obtained from the book and the freely accessible parts of the website, as well as watching Jon's videos on Youtube and free recordings of teleclasses on BlogTalkRadio.
I bought Jon's book for a friend recently and she was so excited, but then she wanted to go back to Tony Ferguson meal replacements (if you are in Australia or the UK you probably know who I am talking about), but I reminded her that Tony Ferguson, Weight Watchers, Gloria Marshall and all those other calorie cutting/calorie watching/meal replacing businesses are only in it for the money. Their methods may work temporarily (or permanently for the rare few) but they are successful businesses because so many dieters fail and they go back again and again, blaming themselves for being lazy, for eating too much, for having no self control etc.
This is where the Gabriel Method sets itself apart from the rest. The focus isn't on restrictions of certain foods or counting points/calories, the focus is on ADDING - live food (fruit/veg), protein (and yes, there are options for vegetarians!) and Omega 3 fats at every meal. Also acknowledging the real reasons why your body decided that it was safer to gain weight in the first place - often it can be a psychological or hormonal reason.
For me, the primary reason I have carried extra weight since childhood is PCOS (polycystic ovarian syndrome) - until the age of about 10 I was a normal sized kid, active and healthy. As soon as puberty hit at 11, that's when the weight started to creep on, then it REALLY piled on in my early 20's when I started taking the Pill. Biggest mistake of my life, it has ruined my body and wreaked havoc with my fertility. I am combining the Gabriel Method with a focus on foods appropriate for women suffering from PCOS and the results are showing.
So if you are considering buying this book, DO IT. It might just work where other books or fads have failed.