Episode Aigis is not worth it at all. It just adds an extra layer to the P3 ending that feels like a made up excuse to produce it. I don't find it satifying nor interesting.
Also you get some flashbacks from the characters' past that are ok. Feel free to watch them on Youtube.
Gameplay-wise it's just more Tartarus with a new character and no personas or items from your P3 run. That's it.

Очан полный.