It's got a cool concept, but it's incredibly oppressive on hero management. Ruptures are everywhere so attrition is high in battle, you've gotta fling your very limited heroes off to all the kingdom stuff and each of them are there for good, and they have a chance of just dying really young and needing replacing which further drains your hero stock.

And the babies they make are all one class, so if you want another class, you better hope you've got that specific class to throw into the Keep for the rest of their life.