Theon and Arya's storylines have not been boring at all. Especially Arya's. Jesus, did you not see what all her character went through last season? She actually probably had the most interesting arc of any character last season.
There are times where I want to kill Theon, but ultimately he's a good person whose been very misguided. I don't entirely blame him either considering what he has gone through, and meeting his father for the first time as an adult, etc. You can tell he realizes just what he's done though, and who his true father is (as he said).
The only boring character in this series is Sansa. I'm anxious to see what comes of her relationship with Margaery and Loras Tyrell though.
Anyway, DAMN! Great episode. Especially that ending. Played out pretty much exactly as I expected, but that didn't make it any less awesome.
It's really satisfying to finally see Danaerys leading an army with her three dragons flying above her.