I really loved the ending. The story was touching, especially the ending with old Zero. Gah! Everything about this series was epic, but the end was seriously perfect. I especially loved the hints of Askad in this and how it is hinted at that Kary never got over his death.
There part with Zero and Omega at the end. Just wow. Really, there is so much I can say about this, but it would be filled with spoilers, so I'll just say I loved it.