I love this show a lot. It is one of the best shows in the DC animated Universe. I like the idea of how a robot realizes that he doesn't want to kill anymore. Also I like the plot line where the authorities think that he has been reprogrammed by the enemies but he wasn't and the surprising twist was that he chose not to kill anymore. I like the idea of Zeta being aware and knowing what is right and wrong in the process. Another aspect also for Zeta alongside his sidekick Ro was to find the his creator as they are again pursued by the authorities. My favorite model of Zeta was the one they used in Batman Beyond where his head is shaped as a the letter U rather than the typical head he has in his own spin off show. They should have used the u shaped head in the show because it looked lot more distinguishing. The only thing I was disappointed with the show was that it didn't end properly since there was a lot of unresolved plots that weren't finished. Pretty much the story ended in a cliffhanger. I also like how they made the connection in Justice League Unlimited where the Justice league members actually use the the Zeta Prototype for there practice simulation in the battle.
