I did SW years ago and whilst I lost 14lbs and quite enjoyed the social aspect of it, the diet is not sustainable (I quickly gained it all back + vat).
Our leader was very keen on the drink and would rave about how you can save your Syns throughout the week and spend them on booze at the weekend. She had twig limbs and a bloated belly. God knows what the state of her internal organs was. Health is not all about the numbers on the scale.
I've lost over 40lbs on my own, and am almost at a healthy BMI. Shifting the last 15lbs is proving hard though.
But if I can give advice having got this far, I'd say to exercise as much as you can. It's true that "you can't outrun a bad diet" but when you put a good diet hand in hand with exercise, you're losing weight and toning up and boosting self-esteem. Don't wait until you've lost x amount of pounds to start exercising as I did for so long. It's hard though I know- modern life is sedentary and exhausting at the same time. Foodwise, don't deprive yourself of anything, but do have everything in moderation.
Also, I DETEST "light" versions of products. If you're gonna "syn", syn properly!