I don't have a Vita (or a Playstation, for that matter....*yet*), but being able to play Aveline's story, even as DLC, is yet another selling point for PS4 for me. Wondering what era it will be set in, though, since Edward's story takes place circa 1710-1720, and Liberation was 1765-1777.
Also, did anyone catch that interview on Sessler's channel where the developer said that the Animus is still in AC4? Desmond's no longer there, but you get sort of a "first person" look at the Animus instead of looking through Desmond's point of view. The dev also said that Edward does something in the past that has a major impact on the Assassins and Templars in the present and future, and that there's a specific and sinister reason why his Animus is chosen for exploration.