This is a well thought out episode. It focuses on friendship and how life might have been if Shego had turned out good and her brothers evil. And we have a brand new villian, who is eletric.
This episode is the best of season 4 because it introduces new characters, brings back evil Ron XD, and shows Shego in a different light. The final showdown with Team Go (now evil) and Shego (now good) and Kim and Ron, was cleverly done and the best fight scene that ive seen in years. Seeing Shego cry was tearjerking, because you dont see her cry that often!
Watch this episode if you havent already, its worth it.