In Batman the Animated series many characters went through a redesign here are the pros and cons
Pros.
Poison Ivy: She just looks so much more dark, seductive, plantish and villainous.
Catwoman: Like poison Ivy catwoman's costume is now darker and she is paler. My description may not be that good but lookat the picture of her up it rocks.
Old cat woman
Old Ivy
Scarecrow: He may no-longer look like a scarecrow but he's just so much scarier, and awesomer.
Croc: I never really liked the old croc look with the grey and the warts he did'nt really apeal to me but the new is Killer Croc
Cons:
I'm not even putting pictures because they suck so much
Joker: Colorless
Ventriliquist: Noone has a hed that flat!!!
Old scarecrow