The A.V. Club is as useful an example as any in terms of positive criticism that takes the show more seriously than that. I believe both Slate and Salon have similar coverage each week. But, honestly, it is hard to believe you have read many reviews of the show if that is your impression of its positive feedback among critics. You seem to see what you want to see.
A second point, worth emphasizing, is that Game of Thrones
is curtrently the most pirated television series on the air. 4.3 million people downloaded the season two finale, and piracy of the third season is anticipated to be even greater than it was last year.