Overall Gotham Nights isn't as good as The Animated Series. For starters the show has been over sylized, so much so that it loses the heart and feel that TAS had.
Some key examples of this would be the new Batmobile, Joker, Poison Ivy and Harley. The Characters don't have the depth they had in TAS, they come off as silly little cartoon characters. And the Joker keeps coming off as a common thug, not the Psychotic genius he should be. Bruce Wayne is too cold and calculating instead of a tortured soul fighting for justice. But the show has its ups, Some of the storylines really benefit from the increased flexibility offered by WB. The crossover with supergirl really shows this. And the inclusion of Nightwing is awesome, he really adds some much needed depth to the show.