I thought it was pretty entertaining, but I personally don't think there has ever been a particularly amazing or terrible Disgaea story to begin with. I feel like all Disgaea games have a more or less equally silly, lighthearted and enjoyable premise and cast.
They haven't been terrible, but Disgaea 1 was magic as far as I'm concerned. So packed with humor and an excellently realized idea of the world. You go from a completely silly plotpoint to the next completely silly plotpoint, full of laugh out loud hilarious dialog. There's a level where Laharl is weakened because there are boobs in the vicinity for christ sake. That's hilarious. The story is constantly moving to give you an excuse to quickly be involved with some other completely stupid thing. "Everyone wants to kill the main character now, so here's a level where every single point on the map has an enemy in it. That's funny, right? Okay, let's go to space now."
I loved that.
Disgaea 2 was still good. I didn't like Adell because he was a hero cliche in a not the-funny-Captain-Gordon-from-Disgaea-1 sort of way, but the game still had Rozalin and Tink to add to the silliness. Since the characters all had one specific goal from the start of the game, they spent most of their time going from point A to B fighting random battles in between and less time on tangents and random silliness like the whole bit with Mid-Boss in Disgaea 1.
Mao in Disgaea 3 was like a poor man's Laharl. That just made me want to play 1 again. Almaz was like a more whiny Adell. Raspberyl just wishes she could be Etna. All of the characters seemed like replacements for the things I love about this series. The story is 85% about
literally opening up your heart, which is a funny idea in concept, but I couldn't help but feel that this would have been a small tangent of 3 levels in Disgaea 1 where they would have gotten the laugh out of me as the game quickly moves on to something else silly. The whole bit with Mao not wanting to open up but then opening up also just reeks of Laharl. All of Disgaea 3 just made me want to play 1 again.