In Mirror's Edge, I sometimes jumped off buildings just to hear Faith break every bone in her body. I hated EVERY character in that game, and was sorry they weren't all caught and executed (that could make a satisfying sequel, though).
You know the writers have gone horribly wrong when you find yourself cheering for the antagonists.
As for enjoying the demise of a villain, I greatly enjoyed watching Johnny Gat taking care of that brat Shogo in Saint's Row 2. That was brutal.
(Come to think of it, SR2 had several truly great villain-killing moments. Jessica's fate was another high point, not to mention the final boss and the end of the "secret" mission. Can't recommend this one highly enough.)