Portrait of Ruin continues the Castlevania version of platforming (read: slaying an ungodly amount of mythical beasts), and also sports a new feature: the ability to switch between two characters freely. This allowed developers to implement powerful dual attacks, as well as cooperative multiplayer over Wi-Fi that allowed you to tag team Dracula with a friend. Or an enemy. Whatever floats your boat.
FUN FACT: Let there be...voice! Portrait of Ruin introduced English voiceover to the series on handhelds.