There's a good summary of Weight Watchers, the Atkins Diet, and other weight-loss plans on Kuro5hin . I've been a Weight Watchers member for a few months, and as I said in my response, it's a gimmick to get you to pay attention to what you eat, under the premise that you'll shovel less junk into your gaping maw if you have to think about it beforehand.
I fought against joining for a while, but my Jabba the Hutt impression was becoming a little too good, so my wife and I attend their weekly meetings at $11 a pop. I'm one of the only guys; it feels like being in the audience at an Oprah taping. The results have been scary: 35 pounds in four months.
The only drawback is that I'm constantly daydreaming about cheese pizza, New York style, swimming in a mouth-watering sea of grease.