I find weird to see people struggling to defeat Vita. I finished the battle pretty quickly and without problem. 3 level 50 skells, 1 30 level skell. My character, Elma and Lin are level 60 and Irina was level 50-53. Lao on the other hand, took me a while to understand that the last part was a fight with no skell, but still was not difficult (just killed Irina, but she had no augments or anything worth it like Elma and Lin). Reading you guys I discovered that Vita has a shield.
Anyway, I finished last weekend and holy shit. That plot twist at the end. Elma was an alien (and I love both designs). Also the last plot twist with the database in the lifehold and Lao's final scene.