There's an episode or two in every season of a show that's just there -- nothing bad, nothing great. Senate Spy is one of those episodes. The show is significant, though, for two reasons.
First, it's the creative team's first attempt at making an episode without a single action scene. I wonder how that played to kids -- especially since the episode focuses on Anakin and Padme's relationship, which I'm sure kids find "icky." Of course, that isn't surprising, since adults found their romance in the prequels to be icky as well.
That being said, the dialog for Anakin and Padme's scenes here is better -- much better -- than the movies, and the voice actors are actually an improvement over Hayden Christensen and Natalie Portman. Their first scene together is surprisingly successful.
The second curious thing about Senate Spy is that it's a direct homage to Alfred Hitchcock's Notorious. I don't know whose idea that was, but they got moxie. Not just for attempting -- and mostly succeeding -- to adapt that story into a kids' show, but mostly for the fact that this episode skirts the line between "homage" and "blatant rip-off." While abridged and adapted for Star Wars, Spy's final act lifts whole lines and camera angles from Notorious. I'm unable to pass judgment on these guys, since a genuine affection for Notorious is obvious, but one could possibly make a case for copyright infringement here.
The real problem with this episode is that it lacks the central hook of Notorious: Ingrid Bergman's character actually seduces and marries the traitor, and she becomes the man's penis receptacle for an indeterminate amount of time, while Cary Grant is torn between his feelings and his duty. Without this hook, Senate Spy is an incredibly odd yet tame Star Wars story: we know Padme would never cheat on Anakin in this episode, that Anakin would do anything to protect her, and yet Anakin is fated to kill her a few years later.