I want to like this episode, a lot. It's yet another Katara episode (at least partly), it focuses both on Katara's past and her interesting relationship with Zuko, it deals with and resolves an issue that was brought up way back in the very first episode of the show, and it displays some awesome waterbending, including Katara bloodbending again. It really want to like it.
The opening of this episode is as genius as it is awesome. Azula attacks the Western Air Temple, forcing the large group that has gathered over time to split up again. I really like it, because it refocuses the show to the few characters that we all know, and reintroduces the leitmotif of travel that has been such a large part of the show. Of course, the animations during Zuko and Azula's battle are great as well.
The premise of this episode is very intriguing, because Zuko manages to dig up an event so far in the past that it happened before the show, and yet has an effect on it time and again. Katara's and Sokka's mother actually appears on screen, has a name, and we find out what happened to her. Indeed, the flashbacks were one of the strong points of this episode. We get to see the same event from three different views, and together they create a very well rounded image of the past.
The execution of Katara's and Zuko's field trip, on the other hand, is pretty poor. Not much happens, actually, and yet the episode seems rushed. There are no big action scenes, just some display of awesome waterbending, and not a lot of tension. Still the pacing feels off. Plot-wise, the events happening in the present are rather thin, and seem devoid of any heavy emotions. Which is ironic, really, seeing as how this episode is all about Katara dealing with her emotions and her past.
I guess one of the things that killed this episode was its hype. Throughout most of the fandom, this was the episode known for having bloodbending. To be honest, the bloodbending was both good and bad for the episode. Ever since 'The Puppetmaster', fans knew that Katara would have to use this technique again. And it's great to see this speculation come true. Just seeing Katara actually bloodbend again is a great moment. However, the actual bloodbending was highly disappointing. It has become a big part of Katara, some technique from the "dark side" that requires an important moment to use. But instead of bloodbending to save someone she loves, she uses it to unleash her anger on some nameless minor character of no importance whatsoever. I was slightly disappointed about how this aspect of her was treated.
Another inelegant move was the whole treatment of the subject of this episode. Katara is supposed to be undergoing a journey of coming to terms with her past and herself, to confront it and to deal with it. Yet somehow, there is no emotional connection, just an objective view of the unfolding events. The dialog might be heavy, but the feeling is all wrong. Which means that this very significant step in Katara's life is just another adventure on the way to the finale.
In the end, 'The Southern Raiders' is a two-sided coin. It was some of the best animations of the show, some excellent dialog (something that cannot be overlooked), and a very interesting ending. But in light of the finale looming ahead, and by the way the story was told, this episode fails to sink in. It just doesn't have the necessary impact it should have, given the topic, and so, even with it being a Katara episode, it is a low point in the second half of season three.