The book A Game of Thrones had minimal magic so it was more forgivable with Season 1. I actually have very few criticisms with the show's first year. Pretty much entirely faithful, and the stuff they did add was great. Robert and Cersei's conversation, the witty Littlefinger/Varys conversations, and a lot more Jaime than in the first book. Then Season 2 was just... a mess. Theon's stuff was well done but every other plotline was fucked with too much. Season 3 was a huge improvement. Though some of my favourite characters were ruined, such as Sansa and Stannis, it was much better paced and highly enjoyable. They got Jaime spot-on, though I've no idea how they're gonna excuse him not rescuing Sansa from King's Landing.