I kinda wanted to comment more on why I like the game so much, but I didn't have the time then, and right now I'm not in the sort of 'mind' of describing it, so I'll get back to this later. Suffice to say, I enjoy the game in part, because, despite it being rather unbalancing, its an extremely flexible fighter with a great diversity of characters to play with.
EDIT:
Dissidia is a great game in general. Lots of characters to play around with, and each one has a fairly distinctive fighting style and unique way of playing that differs from other members of the cast. The ability to customize a fighter's moves and create a unique style of your own that differs from another player's is a big plus. The addition of a fairly interesting storyline as well as including the original story from the first game is a pretty big plus too.
Its not without its share of problems - the huge grind, way too many items to keep track of, the unfair bonuses awarded to higher level characters vs. lower level ones, and the character balance - but Dissidia duodecim does, it does fairly well. While its a shame that there will not be another game like Dissidia (at least for some time), what's offered in this package should keep people satisfied and returning to the game for years to come, I suspect.