Karen Joy Fowler writes very literary speculative fiction--heavy on character development, speculation to enhance it. This is the pattern in We Are All Completely Beside Ourselves as well.
The narrator, Rosemary, takes us through her life, which is challenging but not particularly extraordinary until she reveals that her sister was, in fact, a chimp. Taken in as her psychologist father's experiment. Her complex relationship with her sister and mostly absent brother carries us through the book.
We get to know Rosemary awfully well. She's not a particularly colorful person--not close to anyone, not violent, not...really very much. Her life is a reflection of the people (and primate) around her, and she pretty much knows it. Rosemary seems a familiar sort--a rather dry person who simply never expects to be happy, and made peace with that a long time ago.
It's pretty challenging to make an interesting story out of such a person, with no gunfire or magic to sustain it, but Fowler manages it pretty well. The book is entertaining and satisfying in a personal sort of way.
I'm not sure how I feel after finishing--not exhilarated, or bored, or intrigued. Just there. Rosemary and her ape sister Fern make their animal rights point fairly gently and move on. Read this as an interesting side track.