I was on WW for over a year. I've lost 53 pounds. That being said, I gained weight when the switched to the new Points Plus plan. So I quit and went back to the old points which was obviously working. I'm right now back to my pre-Christmas weight which is 53 pounds down. So I'm not paying anymore but still following the "old" plan.
And I also use
http://myfitnesspal.com which is free and still makes me feel accountable.