This is the first episode that really hit me hard and it's all to do with the fact that the Zuko storyline is the most consistently well handled plotline of the entire season. Dallas Liu plays a somewhat softer version of Zuko, but he has continually infused him with nuance and complexity. In one second he is hot-headed and temperamental and in another he is reserved and contemplative. He often sticks to a code of honor, but sometimes goes against his own code in order to achieve what he wants. All this to say, Dallas Liu does a great job as Zuko in this and the past episodes. This episode deals with his severe inner conflict and reveals the trauma that put him on the quest to capture Aang in the first place. There were a couple moments where I teared up, because of Liu's visceral portrayal of Zuko's deep inner pain.
The experience, however, is somewhat hampered by Gordon Cormier, who plays Aang, not being able to quite match Liu's performance and a rushed resolution to the Koh the Face Stealer plotline, but it is made up for by the quite excellent character study. Daniel Dae Kim also does a great job playing the cold-blooded, ruthless Ozai who thinks the horrible things he does are for their own good. This is a slightly different take on the original character who was even more sociopathic than his live-action counterpart (Ozai in the animated show didn't hurt Zuko for his own good- he did it merely to punish him for Zuko "disrespecting" him). This is a change, however, that I think works to make Ozai more of a fully fleshed out character, because his animated counterpart was a little two-dimensional and we never really got to know him that well.