Killia just isn't working for me as a main character. He's so serious its like he's blatantly unaware he's in a Disgaea game which is extremely out of character for every character in the series. His voice is also so monotone.
Kilia aside, the rest of the cast is great. The extremely snobby rich girl, the third person musclehead saying SUPER all the time and a demon who most definitely is NOT an angel, and who's voiced by the Smash announcer.
I'm very intrigued about the theory that one of the party members is actually the teenage version of a certain very important friend from the first game. The ending clearly says he will get a promotion and will one day play a big role in a certain event. The games narration is also somewhat like a history lesson which implies it takes place in the past.