Disgaea 2's a good game, though I'd wait for the PSP version for some of the Disgaea 3 features that make the game way easier to customize.
Anyway, I won't really defend the game's penchant for grinding (since it really does require it) but once I got the hang of what I should focus on, clearing the game and powerleveling became ridiculously easy. In Disgaea 1 you're supposed to focus on maxing out your character's stats (counters, movement range, jump height, etc.) then getting the best defense items. In Disgaea 2, you focus again on your characters, but items also require nurturing or you'll end up getting your ass whooped. In Disgaea 3, special attacks are key to dealing immense damage since they ignore defense and resistance as opposed to the previous installments.
Disgaea 3 made it way easier to level up multiple characters at once, too. With the advent of the classroom, they made it possible for any character to leech EXP or Mana gained by the character they're sitting next to. When you couple that with the ability to dupe/farm specialists (specifically the ones that greatly increas EXP and Mana gain), you're laughing.
My current setup, while not the best, allows me to go from level 1 to 9999 in fifteen minutes. Total playtime? Just under 80 hours. Pioneers in guide creation and research for Disgaea 3 only managed that in hundreds of hours, but I reaped the benefits of playing through the game nearly a year after its release.
On a side note, the trophy patch was announced for Disgaea 3. As expected, it's not newbie friendly at all (a bronze trophy requires dealing one million damage to a single unit, while the gold trophy version requires dealing ten BILLION).
Formerly known as: Gothann