Disgaea 2 is a great game with plenty of depth and humor.
Gameplay: The gameplay is fun and interesting with plenty of interesting special and team attacks. It's one of those games that's actually pretty fun to grind. There's a lot of depth and things to do, and the item descriptions are just wonderful. There's also quite a few secrets. >:)
Story: The story seems pretty uninteresting at first, but it starts to grow on you and before you know it, you have an interesting story. With humor and witty dialogue in tact.
Characters: The characters are all interesting. Especially considering you have Etna, Laharl, and Flonne in here. And of course, who can't love the PRINNIES. The Prinnies are The. Best. Video. Game. Monster. Ever. Penguins..that talk..and say "dood" a lot..and have little bat wings..and a satchel like thing with swords and bombs..and they explode..Amazing. Oh, and they drop pans on people's heads. There's plenty of characters that you can create, and being able to use any monster you fight in your party is great.
Sound: The voice acting is great, they match the character well. I especially liked Rozalin's voice. The music isn't much of interest, but it's still good.
Disgaea 2 is a great game that's likely to keep you interested for quite a while.