Butter? A superfood? Please. But in my opinion, it is much better for you than margarine, even if the margarine is trans fat free. The ingredients on a tub of margarine, trans fat free or otherwise, are far from natural. I know, I know, natural doesn't mean safe. But I don't think many people with current nutritional knowledge and an understanding of saturated fat would argue that a little butter will kill you faster than margarine.
Since it's a saturated fat, butter is good for cooking at higher heat. If it's from organically raised and 100% grass fed cows it's a great natural source of CLA and 'good' fatty acids (and even some beta-carotene I believe), but most people can't afford that. It's basically like any other high-fat dairy product. Regular butter is full of hormones and antibiotics, but it's still not too bad in moderation.