I watched some youtube videos of heartfire and wasn't too impressed. The building of your house seems to be more mix and match than actual customization and it takes a lot of time and money. Once you've built your large house then what? You can move your spouse and two children in and watch them interact with the environment and that's basically it. They haven't done anything to improve the spouse (you can ask them one new thing - "How are the children?") and you can hear all of the children's dialouge in about five minutes. Other than that there's a bard, house steward and some random events like giant attacks and kidnappings.
I think some of the stuff in hearthfire might annoy players. You can come home and find your steward, bard and spouse all dead. Unless they patched in an option to remarry (I don't think they did), that's it for a spouse. The bard's singing and the chidlren's dialouge (Do you chores - "I don't wanna!") could be annoying. Plus the bugs like when your spouse is rescued after being kidnapped they walk backwards.
I was thinking of picking it up when it's 50 or 75% off but with the possible permadeath of your spouse and various bugs I'll pass.