This one scrapes by to a 7.0/10 because of the cool visuals and sound design work done with the nightsisters, and the pathos of having Ventress lose everything. The vocals of the nightsisters, particularly the demonic echo of Mother Talzin's speech and the creepy tones of Old Daka, were appropriately unnerving, and the raising of the dead sisters to help in combat against the droids made my skin crawl in a delightful way. They captured the herky-jerky zombie movements and made for eerie combatants on the side of the sisters.
But most of the episode was just a big escalating battle, that fell into the video game plotting I've occasionally complained about on this show. We get one stage of combat (the initial assault), followed by another stage (the night sisters take to the trees), followed by another (Grievous uses his ubertank) and so forth and so on to where the whole thing feels like plotless technical exhibition. The fact that the lightsaber battle between Grievous and Ventress, two of Clone Wars's signature baddies, was pretty brief and underwhelming, didn't help the proceedings.
But the end had enough punch to set the episode straight. The whole deal with Mother Talzin using a voodoo doll on Dooku was a bit cheesy, but cutting between that and the assault worked for an interesting visual contrast, and again, there was something tragic about the way the nightsister were slaughtered leaving Ventress all to her lonesome. As a whole, the episode is mostly interchangeable combat, but they put some genuine, if late, character and meaning into it at the end.