I love the GOT, but HOTD seems too plain and just an average, mediocre story. The first episode started strong, but then the quality got lower.
From episode 6, recasting the main characters was unnecessary and disappointing. The storyline doesn't run consistently, it jumps ten years, and another time it provides details. The aging of characters also could have been more consistent. Some aged more than others...
I give it a 2/5 just because I have waited to watch it for too long, and GOT set us much high, so this one is far from it.