I can see the general appeal of the series. You have three female leads with different approaches to leadership and motherhood. The more family orientated Caitlin, the politic and scheming Cersei and the kindly tyranny of Daenerys.
While they are not exactly nuanced they are slightly more fleshed out than their male equivalent who all want power (and the Stark concept of justice is the power to order the world as they would prefer) and see war as the way to obtain it.