Huge GOT fan and disappointed with HOD. GOT was surprising original characters (Aryia, Tyrion, Cersi/Jamie) engaged in complete self-standing, though intersecting, vignettes (Kaleesi/Drogo, Aryia with the hound, Tyrion at the Vail) with surprising original sub-worlds (the wall, Bravos, Yunkai ). HOD characters seem familiar versions of royalty engaged in one familiar storyline of royal succession in one location.
I suppose it is not surprising when we remember, GOT (at least the good part) took Years for G. Martin to flush out and perfect. HOD is the product of a deadline-driven "writer's room."