I think what I'm enjoying the most is that the source material is basically a history book, written by unreliable narrators. You can know EVERYTHING that happens in the story as it was told, but then be blindsided by the ACTUAL events as they happened.
I won't spoil anything, but just like how in the book, a certain event occurs out of malice & hatred, but the show then shows that it was actually, pretty much, an accident. As many occurrences in real life, the event MAY have then been reframed to build the reputation & legend of the character, but either way, I enjoy knowing the story but still being surprised in a good way. Not just having my expectations 'subverted' just to show how 'clever' a writer thinks they are.
Overall, I think this was the strongest episode to episode season of television I've seen in a couple of years, & even though I sometimes thought GoT was a bit of a slog to get through, even when it was 'good', I've already found myself going back & rewatching episodes of HotD.
Long wait for season 2, though.