Our 10-year-old daughter was excited to receive a novel-length Frozen-themed book for Christmas. She told us the story was entertaining, but she felt uncomfortable with the introduction of the lesbian blacksmith characters into that world. At any rate, she returned the book to us.
The openly gay relationship is pretty anachronistic for the 1840s, and I agree with the reviewer who feels the gay theme seems pretty contrived. We don't want to promote homosexuality to our children, but if it were part of our parental agenda, I'd find an author that employs a little more literary artifice.