The more I think about this, the more I'm convinced that what's really getting up my nose about this series is that it's so utterly po-faced. There isn't a whiff of humour in the entire thing, making it horribly portentous and stodgy, and incredibly hard to warm to any of the characters.
I mean, I know Jackson's LotR films mortified any number of Tolkien fans by having actual gags in them, but even GoT had the nouse to invest (at least some of) its characters with a sense of humour. Right from the first episode, with the tension-deflating "You got old"/"You got fat" exchange between Robert and Ned, through any number of Tyrion double-acts (notably Bronn and later Varys), a decent chunk of Arya and the Hound…
This, though… it doesn't seem to have the depth the weighty tone seems to imply we should be finding in it.