Fills you in on the background mechanics of the world in a much simpler way.
Entire cast appears, with all VA's still in their roles.
The animation is also faithful to the official art.
CONS:
The story revolves entirely around Ragna, Jin, Noel, and Hazama. Everyone else is either seen as secondary (Rachel, Kokonoe, Makoto, Lambda, and Tsubaki) or bit-part (everyone else).
For shippers, the studio favors Noel over Rachel for Ragna. Just if you care.
It's a low-budget work. There are some silly animating moments.
As I said, the games still are required playing to get a full grasp of the universe.
Overall, for a fan of the series, Alter Memory is a 7/10. Without prior knowledge of the series... a 5/10.