I will say if you buy X-Edge (Thanks I wasn't the only one who calls it that), it would be for your love of the other franchise.
Personally I will tell you to buy Disgaea 1-3.
Edit: Overall as JRPG person, I think it has a decent challenge, and some funny skits, but the game misses that appeal that most JRPG game....I can't really point out what it is missing, since I don't know myself. (I would call this appeal the hook)









