I lost 35 pounds using the Weight Watchers plan a few years ago. As I understand, they have since changed the plan slightly, but I found it worked really well.
I think the key to using a program like this is to understand that it is more a lifestyle than a diet –– a way of learning to eat in a different way.
I'd definitely recommend it to people to try. As I said, it worked really well for me.
Best of luck!