Well, it's definitely the weakest of the four scores. But it's still pretty great. It absolutely delivers in the field of raw, brutal and chilly northern material - "Watchers On The Wall", "Thenns", "The Biggest Fire The North Has Ever Seen", "Let's Kill Some Crows"... all very, very good tracks.
This score is very dark overall - except for beautiful and awe-striking "The Children" cue, it lacks epic, rousing material like "Mhysa" or "Mother of Dragons". Instead, it's filled with despair, melancholy, adrenaline and horror - one can only guess if either "Oathkeeper" or "He Is Lost" will be played during THE event everyone desperately wants to see (for those who know what I'm talking about, yes, I mean "LS"). The trademark of the show's music - low-playing chello - is literally omnipresent here.
It's a shame that some good cues didn't make it to the soundtrack, like for example the great cue playing at the end of this year's first episode, which combines "The Kingsroad" theme with "Valar Morghulis". Oberyn's theme is also missing, but I guess this is because it will be further developed in Season 5, which will spend a lot of time in Dorne.
My final verdict for now is 7/10 after first couple of listens, but I imagine it will only get better from now on.