Any theme that is tightly associated with real character voices will be a fail to me, just like TWD and Avengers for example... Not using the true voices just kills a theme for me. And I get the feeling that GoT would be just as bad as the other ones because you know they aren't going to use the real actor voices.
And the sad thing? They don't even need to bring the actors in, they could just use audio clips from the movie/show, but even that appears to be too much work.
Tron, Ironman = Awesome voices
TWD, Avengers = crap.
Just my humble opinion, of course.