I really liked the writing, the concept, and the execution.
Except for a few points where it seemed to be hit with a bit of copy pasta from the OGL material, it was extremely well written and organized.
As a horror work for D20 I'd rank it up there with the Ravenloft 3.X Gazetteers in terms of how well it presents a setting, and inspires you to get immersed within it as both a player and game master. Its story blurbs, background write ups, artwork, etc, all add to the ambience and make it have a distinct and original character. I know some may take issue with a few of the setting's historical revisions. However once you arrive at the setting material in the Game Master's section, you are made well aware that this was not meant to be a historically accurate game or setting (in case the undead being a thing were not a big enough clue to begin with), that time period's prejudices and values are not intact here, but an alternative history with fantastical elements added is. So take it or leave it on that point, it was just how the authors chose to exercise their artistic license. (Side note: Also many people are not well studied students of history, and themselves substitute what never was as 'how it REALLY was back then' when criticising works of historical fiction anyhow.)
[4 of 5 Stars!]