I just finished the part of the Fey questline where you have to find the spy, and I have to say that that part was really well done! I don't know if it's a pre-requisite, but having the mind reading power made it even better. It gave hints that were obvious in hindsight, but I still didn't guess the twist before it was actually revealed. Overall, I was really satisfied with how it turned out.
My one complaint, is with Ami being crystalized and being completely fine afterwards. For one, why did she need to even be recycled if the crystal was fully capable of reviving her? Before it's revealed that she's been crystalized, Morgonna claims to have already questioned her and that she didn't know anything. But as the story progresses, we learned that she actually knew exactly who killed her and her last message even pointed it out. Ami was very clearly afraid of dying so I don't see why she'd lie or not reveal the whole truth to Morgonna. So what's the deal?