The villains basically play their roles at top-volume without much range (although Burgess Meredith's FDR/Popeye blend for The Penguin is a stitch *Waugh!*), with the exception of the truly bi-polar performance of Frank Gorshin as the Riddler, practically quivering with psychosis.
One has to acknowledge that if this version of Batman and his villains hadn't been so iconic, film-makers wouldn't have needed to brainstorm so long and hard to come up with a Bat-antidote for the movie versions.
* It's still amazing to see West fill this role with mock-humor. Can you imagine how stuck-in-first this show would be if second-choice Lyle Waggoner had won the role?