He wasn't in Episode 2!
This is a premise where you can simply do no wrong because it combines two things that are really popular on the Internet. The most impressive thing was how all of Darth Vader's lines are always related to what was going on in the situation. I expected Cat Vader to force choke someone. The animation was not the best, but it doesn't matter because it's so darn funny. I especially love watching this little guy point his paws at people. When he was talking to the guy in bed, I thought he was saying, "Growl".
He was actually saying, "Meow" or something like that. There's no real story, it's more of a series of jokes that are used with this character. That's all you need to make this great. I didn't even notice until now how good Cat Vader looks with the whiskers around his helmet. At least his entire body did not get singed, but he is black.