Does Weight Wathcers Really Work?

Basically Im thinking of joining weight watchers. Ive been trying to watch what I eat and have changed my eating habits, plus I do work out, But Im still not losing anything. I want to lose 20 to 30lbs and think the program might give me more motivation. I'm not severly overweight or anything im just now feeling consious of my appearence. Does anyone have any advice or expierence with the program?