The DS version of Disgaea was absolute trout. It's the only version of the game I have yet to beat. Purchase one of the newer versions for the PSVita or something. Phantom Brave and Makai Kingdom are great, but they are gridless. The Growlanser series is tactical and gridless, but those games are fantastic. The only issue is that very few of them get ported. If you still have a PS2, you should pick up Growlanser Generations.

tldr;

Forget about Disgaea DS and try one of the other ports. The PSP version is the best out of the 3.