Hearthfire is worth the 400 Microsoft Points
The best feature by far for me is the ability to adopt children but you can only adopt 2 children so choose wisely. Yes some people will say "Why can't we just make our own children." You tell me how your going to do that because remember you can have same-sex marriages in Skyrim. You can buy your children clothes, sweets and toys. Once I came home to find my two children cussing each other so I told them off -_-
However overall I think Hearthfire is a great addition to an already brilliant game.