This is a reissue of a book that was first published some time before the only other novel that I can compare it to, Susanna Clarke's Jonathan Strange and Mr Norrel. Both combine the doings of society gentlefolk (and their less elevated contemporaries) with menacing folkloric elements and magic; both are set in that neglected (in fantasy) Regency period (though Goblin Moon is set in an imagined world that is intended to feel like northern Europe of the late 18th century); and both have a strong narrative voice that gives the feel of literature of that period.
I have to say that having looked again at Clarke's book, Edgerton's language feels more authentic and is certainly more elegant. The narrative voice is almost a character in its own right: lushly descriptive and perfectly poised. This narrative style might be off-putting to those who want the kind of immediate identification with character that's possible with a close-in point of view; but it would be a shame if they were put off, as though it takes a while (or did in my case) to really sympathise with the characters and worry about their fates, by the time that happened it was the icing on an already delicious cake.
The plot itself has two main strands: the efforts of Miss Sera Vorder to discover the dark machinations that lie behind the betrothal of her cousin, and the work of Sera's alchemist grandfather to create a homunculus. So twisted is the plot (though rarely difficult to follow) that it seems incredible that the book is only 300 pages. Despite the lavish description, the alchemical details etc, the style is actually very economical, and the story never drags. This economy is one way that it differs from Clarke's book; it is also set in a world where the fantasy element is much more obvious than in the Regency England of Strange and Norrel, and in which men live alongside dwarves and gnomes, and hobgoblins are a known danger at new moon.
So why not five stars? As mentioned above, the narrative voice, despite its advantages, does slightly hinder really getting into the characters' heads; it also has the effect of slightly prettying the darkness: evil seems perhaps less evil when so elegantly described. There were also a couple of occasions which seemed to merit stronger drama than they got.
But these quibbles are all far outweighed by the book's many strengths, and I would give it 9 out of 10 if possible. All in all, it's a very good read, and so original and different that it deserves to be tried by everyone. Where else could you encounter a "gentleman troll"?