I think that SW is the most un-diet like diet I have found and I think a lot of its success is in the psychology - by having unlimited free foods (for me at least) there isn't any danger of "running out" of food (either points or cals etc), and knowing you could eat the whole lot means that (again for me) I find I don't need to.
I think that you do need to use a modicum of common sense with it, and if you are eating packets and packets of pasta, 10's of Mullerlights etc every day you're probably not going to have much weight loss. But if you follow the rules, you should naturally be eating much less (cal wise) because it is mainly low fat, low cal stuff.
I eat quite a bit, but sometimes I don't actually eat enough calorie wise, because it is healthy food, and because I am quite big still I need more calories or it is too low. As you are a man, you would also need to be eating slightly more calories, so you might need a bit bigger potato, or extra rice.
The main thing is if you are losing? If you are then you can't be overeating?
And as others have said, try to get used to listening to your body - stop when you are full and don't eat just because it's free.