Ultimecia makes for one fo Final Fantasies more... interesting super villains. In the entire series, I can only think of one other game where the player can go so long without knowing who he is fighting, and that is Final Fantasy 4. If you ask me, not seeing your enemy until the very last battle does not make for a good story. I personally think it would have been much better if Seifer had become the ultimate bad guy. Just think: if Seifer had somehow become the first Sorcerer, he would have been the perfect combination of Kefka and Sephiroth. Square could have done great things with Seifer, even bringing more on Rinoa's fling with him into light, but they chose instead to give us an intangible enemy. That is really all I can say about Ultimecia. Any of the other 2 we know about her would be a spoiler.