Little late to the party, but wanted to add my two cents. Only read a few posts but it reminded me what I disliked about the premiere so wanted to get it out before I forgot then go back and read.
I was a bit disappointed by some of the scenes. GOT I always felt was about the story, not the characters, and the way they are portrayed in the show tends to be distinctly different, so as to almost twist some of the plots. Were I just watching the show I would feel differently about some of the characters. Major scenes for example were the Littlefinger/Sansa scene which never happens, and it takes almost the whole entire goddamn book to find out Littlefinger orchestrated the death of joffrey + got sansa out etc. This is sort of integral to his character, in that he actually has his hands in an abnormal amount of things, that you *never* know about until much later, and and/or don't even suspect him. (Joff's death, Jon Arryn's death, certain things in the vale, etc.)
I can only assume that due to things they've already revealed about Petyr that don't become known till later, that they want to make sure you understand that perhaps one of the things, or maybe the only thing that motivates Petyr is his love for Cat. The conversation didn't take place, but not only did they change Petyr's role in it, but they made Sansa out to be relatively bitter at that point, yet she's NOT QUITE there in the book. That might seem small but to me it made me feel different about her character.
The exchange between Tywin and Tyrion was another good example. It's obvious Tywin is not fond of Tyrion, but it makes him out to be a bit more openly aggressive whereas he's mainly passive aggressive in the book. Also, Tywin tends to do shitty things but he's not a total loss and I tend to respect him, because at the very least he aims for strong leadership for the kingdoms.
Also, someone correct me if I am wrong, but the Melisandre/Davos part was changed no? I don't remember him getting thrown into a cell though it's been awhile since I've read the book.
Selmy meeting Dany also was done differently - I suppose they had to show Selmy since once he met Dany it would be clear to the audience who it was, but I always regarded that time that he follows her as "sizing her up". I think he says he seeks her out because he was thrown out and had served her family before, and wanted to see if she was a worthy ruler or something? Either way, him just running after her and immediately offering her his sword didn't feel true to his character. Lol rebound queen?
I always told people not to worry too much about reading the book. That they definitely SHOULD, but that the show was enjoyable all on it's own. I still think that, but I think they are getting a watered down version in a way and that kind of makes me sad.
Martin makes all of these characters and all of these things so subtle, and then the tv show sort of takes that away. Meh.
Also, as mentioned, yea Tywin helped with the red wedding, but I am fairly sure based on his convo with tyrion in the book that he did not plan how it went. From what I remember it was very much a, "If anything untoward should befall the young wolf I might somehow find marriages and whatnot for your family etc." I believe he actually tells Tyrion something along the lines of "That was how they did it, so the dishonor is on them."
As far as catelyn, she deserves all the hatred. The biggest thing about her character is that she does the very opposite of what she should do, but KNOWS it. Eddard made stupid decisions, but he believed them to be the right path, for the good of all, the least likely to cause harm to anyone, and/or the most honorable way. If anything, his worst crime was in underestimating people and not realizing what assholes they all are. Also, realize that when he did the shit etc with cersei he was not expecting Robert to die suddenly, so...for example, when he tells cersei to leave, and thus ensures his death, this is all thinking that Robert will listen to him, he'll handle it, but he knows Robert would kick their asses so he gives them warning.
Catelyn on the other hand spends many pages in her POV stating how she knows the lannisters are that evil and yada yada yada and STILL DOES IT ANYWAYS. She mentions enough that you are fairly certain she knows what the consequences will be and carries on. So honestly, she doesn't really do things for the sake of her family, because if she HAD, she would have handled things much differently. Everything that happens from then on out is literally in reaction to her idiocy, and not only does she NEVER think that what she does is a terrible idea, but she goes behind other people's backs to do retarded things. She's lucky that somewhere along the line Jaime found his honor, because otherwise she would have been in so far over her head letting him go. As it is, I firmly believe the red wedding would have gone down differently had jaime still been a prisoner when they arrived.
It's part of the reason the book is so important; only with internal monologues do you have the ability to either dismiss or accept the reasons people have and the things they do. Catelyn however, spent a lot of her POVs telling you how she knew 2+2 = 4 and still was going to make it equal 5. That's not intelligent, and she started an entire war over it.