I think most of the folks new to Game of Thrones will be focusing on the moment in yesterday's episode when Viserys Targaryen suffers a gruesome death by having a pot of molten gold poured over his head. As uncomfortable as that was to watch, it was really tame compared to the image I had painted in my head when reading the book.
In the grand scheme of things, though, Viserys' death is rather minor. If there's an event in last week's episode that I would point to as most significant to the series itself, it's when sellsword Bronn makes easy work of Ser Vardis Egan, dodging his clumsy blows before thrusting his sword into a chink in his armor and kicking him into the sky. Lady Lysa Arryn, enraged, yells, "You don't fight with honor!" Bronn dryly responds, "No. He did," gesturing to the thousand-foot drop he just dropped Ser Egan into.
This is one of the more startling aspects of A Song of Ice And Fire. When you play the game of thrones, you win or you lose. Honor doesn't even enter into it.