Loved the depth they added to Ventress.
Weeeelll...they added that depth with an eyedropper...but hey, it's a step in the right direction!
Until and unless Ventress becomes a fully fledged or even partially fledged character, it's going to be hard to become emotionally invested in her quest for vengeance (especially since we know she can't kill Dooku anyway). The problem is, I still don't know who she is, really. Her personality seems interchangeable with Dooku's. That's a problem with
Star Wars baddies' overall. They are just cardboard props who want power (if Sith or aspiring Sith) or money (everyone else). A good character should have behavior and goals that are distinct from every other character in a story. That's how a character becomes more than just a prop.
Compare this plotline to, say, a
DS9 story arc where Dukat decides to get vengeance against Weyoun (or vice versa for that matter). That would be hysterical fun, because both are well delineated personalities, in no way interchangeable, with unique ways of behaving and even speaking, and very different goals in life. The story would have to be specific to those characters, and would be quite different depending on which character was the one seeking revenge.
Star Wars still has a ways to go before they start having
DS9-level villains who can steal the show from the heroes.
OTOH, Ventress is an impressive badass, isn't she? Took on Obi-Wan and Anakin, while injured! You go, girl!

Also, I suspect that there's a larger agenda at work here, possibly leading to the greater delineation of Sith characters and the Dark Side that this series desperately needs. So I'll be patient and wait to see what the next two episodes deliver. It's hard for a story to get anywhere in half an hour, minus the necessary lightsaber/space battles, minus the toy ads.
I've never heard of the Nightsisters before. If they are Force users, then that makes a certain amount of sense. Why should everyone have to be shoehorned into Jedi or Sith roles? And they also defy the idea of simplistic good or evil. They don't seem nice, necessarily, but they do have a lot of loyalty towards each other, the way they immediately jumped on Ventress' vengeance bandwagon without any quibble about whether it was their fight.