Light spoilers.
This was a chilling experience. Going from the lack of choice to seemingly infinite choice gave me some very powerful emotions. The story was simple, but I loved Didi's slow descent as she searched for Gogo. I very much enjoyed the piece and it's easily in the runnings for the best horror novel in the jam.
As for suggestions for improvement, I think the permutations started to blend together, with the same concept being played out over and over again, even when the content was "new." I'm sure that was part of the vision, but I admit I did start getting frustrated and it hampered my overall enjoyment of the project. But overall, the strengths of the novel far outweigh the frustrations.
Thanks for the fun read!