However, on my low fat/exercise diet, I lost fifteen pounts my first month.
The problem with the Atkins diet is that if you get off it, you're very likely to gain your weight back rather quickly.
FF, You will gain the weight back very quickly if you quit any diet and go back to your old way of eating. A diet cannot work if you aren't on it. That is not a problem with Atkins, but with human physiology.
That wasn't my experience, but the low-carb philosophy holds that for many people, low-fat, high-carbohydrate ways of life are a disaster. The past 30 years of American life seem to bear that out. It doesn't matter whether the carbs come in the form of potatoes, breads, or Gummi Bears. To the body, they're pretty much the same. Thus it would be no surprise to find that the weight comes back on rather quickly once high quantities of carbs are reintroduced.
This bounce-back not a failure of the Atkins diet, but a failure of the standard American diet. Kind of like saying: "I feel better when I stop banging my head against the wall, but when I start banging my head again, it hurts; therefore, it's bad for me to stop banging my head against the wall."
I'm not out to convert anyone else. People have different metabolisms, so your mileage may vary. If someone does well with low-fat diets, then that's what they should do. If I ever stop doing well with a higher-protein diet, then I'll do something else.