I'm not too engaged by this storyline, though I guess it's okay. It is a good idea to confront Anakin's feelings about his past as a slave, but it doesn't seem to be getting confronted enough. And I still have trouble getting past the whole "distinguishing alien species by giving them regional Earth accents" thing.
I could've also used a better answer to Ahsoka's question of why anyone would need live slaves in a high-tech society -- especially when they have trillions of droids that are already essentially slaves. Sure, the whaddayacallem cat people, the Zygerrians or whatever, do it for the profit of selling slaves to others, but why do those others need them? Is it purely a luxury item, something people want merely so they can have a power trip by bossing other beings around? The queen took that attitude herself, but is that what motivates all her people's customers as well?
Ahsoka could've used some more practice in how to pretend to be a slave. Her contentiousness didn't help sell the illusion any. She did look fantastic in that blue dress, though. Not quite Slave Leia hot, but still lovely. And I love how calm she was meditating in that cage, and that casual Force-telekinesis move she did. (Though if she can throw that guy around so easily with her mind, why can't she use the Force to break that shock collar around her neck?)
The problem is that this series is either Filler or Killer. There are only two actual storylines that require any further attention: "Why Anakin Went Squirrely" and "Ahsoka's Fate." Everything else is just killing time.
If you're looking at it from the perspective of "What does this contribute to the movies' storyline," sure. But if you look at it as its own self-contained work, neither of those is really an issue here at all (except maybe the former, occasionally), and the show has established a number of worthwhile self-contained threads of its own. Ahsoka herself, her journey from callow apprentice to seasoned Jedi, is of course the primary thread, and I'm more interested in that than in the purely technical question of why she's absent from some movies that were made before she was created. But one of the most successful and engaging elements of the show is the one that makes it live up to its subtitle -- the continuing focus on the clones themselves as major characters. I mean, we just got a 4-part,
movie-length story that was almost entirely about the clones, with hardly any of the film series' main characters appearing at all. If ever a story deserved to be called
The Clone Wars, that was it. It really underlined what this show can do with its own characters and continuity, how it can be more than just a fill-in between movies.