This Warhammer pdf is extremely well scanned. It offer a better resolution and leave no blur marks compared to some other Warhammer pdf released on RPGNow (still those are well made and present minor flaws. If you plan to purchase other WFRP pdf here, you can do so with the confidence to get a good product).
Concerning the book "Night's dark masters", you can't be wrong with this sourcebook. It is extremely well made and very pleasant to read. It contain all the background setting you need to know about vampires in the world of Warhammer. It, also, offer a whole chapter to describe the Sylvania region, its people and customs, so that your PC can venture into this bleak land. The book also feature templates for each vampire houses to play a vampire as player character (PC). It offer an interesting system of vampire traits (Blood Gift) that will make each vampire creation (PC or NPC) unique. Beside that, the sourcebook will give you new careers for your traditional PC. It included, as well, a new Dark Magic lore, Lore of Nagash which is a different kind of Necromency, with its proper spell liste. It feature, also, new rituals, magic items, a full detailed map of Sylvania land of the Von Carstein House and a bestiary centered on opponents related to those encounter in Sylvania.
Since the original book was not published in hardcover, this pdf offer you a good solution to preserve your original copy and its information from the entropy and the vicissitude of time. In this case, however, sustainment in blood is not mandatory ; )