One thing that surprised me about was that there is something of the Discworld in this book in that the integration of the undead, and especially Vampires into the cities of the Old World smacks more of Terry Pratchett than it does of my reading of the original WFRP canon from the game books. In the book there is a monastic retreat for vampires, and the undead have their own bar that they frequent in Nuln. There is also a lighthearted tone to much of the novel that also makes me think of Pratchett, even though there is not the same level of humor. Of course WFRP is known for its humour, but in general it comes in a darker more satyrical form in the game material.
Since the protagonist of the novel is a vampire, as are many others in the book, I immediately thought of the use of undead as Player Characters in WFRP. It seems I was not the first, as many others had asked the same question on online forums. They were all met with the same response, at least for 1st ed WFRP. No.
GW thought at the time, and I tend to agree with them now I've thought about it, that vampires are not the right power level for WFRP, and did not at all fit in with the power level or themes of the game. It turns out that for 2nd ed WFRP, in the Vampire Sourcebook, Night's Dark Masters, there are rules for this, even if it pretty much tells you not to use them.
So back to Drachenfels. Back in the day, I may not have read the book, but I did buy the game supplement, Castle Drachenfels. I never ran it, as even then it was clear that it would mean a lot more to you as a player or even a GM, if you had read the book, in the way that is described the castle. As a game book it was also hard to fit into an ongoing campaign, as the Castle itself was nothing but a huge meat-grinder, more reminiscent of a dungeon, or a book of Grimtooth's traps, not quite fitting with the WFRP I played. So I put it on my shelf and did no more.
When I was recently going through my WFRP books, I brought it out again, and was surprised to see that none of the characters in the book are stated out in the game supplement, it really is all about the castle as a dungeon. This seems to me to be a huge oversight by the GW team at the time, as the characters were really well described and fit so well into the Old World, crossing many strata of the society of the Empire, and would have been useful to GMs running many different types of game. Even if they all do mostly die in the book. Where i do see that the castle is a character in the book, in some ways more than Drachenfels himself, the other characters are what actually make the book and the story.
I've since bought the second book that has also been re-released in this series by The Black Library, Genevieve Undead. This contains 3 short stories with the same main protagonist. The first, a direct follow up to Drachenfels "Stage Blood" is a wonderful little story full of ideas for a city adventure based on the acting troupe and their theatre, with themes and plots threads brought in from the Phantom of the Opera. This also has a sympathetic character that is a chaos mutant, just as in Drachenfels. These two characters are great ways to think about mutants in the Old World, a lot of whom are mutated through no fault of their own. Sounds like PCs to me!
The other two stories also have the same main protagonist, the titular Genevieve, are placed in other parts of the Empire, and are good, and can be mined for game ideas, but not directly related to Drachenfels lore.
So, if you're looking for a book that's a good read, or is based in the Old World of Warhammer, or has vampires, then I heartily recommend these books. They have almost single-handedly brought back my interest in running or playing WFRP. So much so that when back in the old country, I dug a bunch of these out of storage in my parent's attic and brought them home, in the hope of finding players.
Of course, if you really like vampires, then you will already have read Kim Newman's "Anno Dracula" series. If you haven't, then go do so now. I'm currently working my way through those too. Indeed, the author states that Genevieve Dieudonné is the same character in both series of novels.
Finally, there is an interview with the author to signal this 30 year anniversary on Youtube.