The frozen throne room was a great image and having Dany travel through the Wall and meet Drogo was a good idea. The sort of things I can see GRRM approving of.

The loss of the foreshadowing for the Red Wedding was silly, though. It's going to be a huge, huge moment next season and the book gave them the perfect ability to set it up really well. Yet they didn't bother (we got the early appearance of the song last week instead). A curious choice.

The lack of Rhaegar/Elia is more understandable: the show has eschewed flashbacks (one was filmed for S1, showing Brandon and Rickard's death, but shelved) and introducing one here, featuring two important characters, would have been tricky to pull off. Them not pushing the buttons on R+L=J on the show may be because in a visual medium it'd be much, much easier for people to guess the answer to it, but that was only a small part of that scene. More important was the first voicing of ice and fire and it gave us a separate confirmation that Melisandre's aims may not be so insane after all. These are things that are important to the show as well as the books and it doesn't help not to have them present.