The villains will be broader and more fanciful than the relatively grounded heroes. They're all comics characters that haven't been seen in animation before, including Anarky, Magpie, an obscure Golden Age villain named Cipher, and Grant Morrison's Pyg and Toad. Some of the characters are reworked/reinvented for the show, particularly a less gruesome version of Pyg and Toad. Toad is played by Udo Kier. Anarky will be the "Moriarty" to Batman's Holmes, a mastermind and manipulator (so he's probably rather altered from the comics' version of the character).
I really like this idea. Because as awesome as Joker, Two-Face, and the rest are, we've seen Batman face off against them so many times by now that it's started to feel a bit tired and routine.
It'll be nice to have some villains where you can't predict every move they make for once.