It's true that this game is incomplete, and sadly, from the sound of it, it might never be completed. But I'm still giving it 5 stars, because it's got some very brilliant ideas. Out of the hundreds of PDFs I've purchased on DriveThruRPG, this is among the handful or so that I've found to be the most interesting. I want to give praise to some of my favorite parts here. (Page numbers will be listed as: print page number/PDF page number)
The book starts off with a discussion of themes (p1/8), which I think every campaign setting should include (and tragically few do). The themes here are interesting both to define what this game is about and as a general discussion of gothic horror fiction.
0-level occupations (p16/23) are an idea shared by most versions of DCC RPG, but this book has an especially interesting interpretation of that idea. Not only does each entry give a short paragraph describing your character's background and occupation, but most of them suggest hooks for why your character might become involved in hunting monsters. Most normal, sane people would not just spontaneously decide to go risk their lives (and their humanity) chasing after monsters, so it's nice to see ideas for how each character might get dragged into that world. Lots of RPGs include lists/tables of character backgrounds, but those almost never include ideas for, "Here's how this character might've gotten dragged into the dangerous world of adventuring." I think it'd be great if more games included that. The 0-level occupations also determine your starting age and wealth level. That will become relevant once you understand the big picture of how "Transylvanian Adventures" campaigns work.
The chapter on "Adventuring in Transylvania" (p143/150) gives you an overview of that big picture. The default campaign setting is a fictional version of Europe in the 1800s where Dracula and/or Dr. Frankenstein could potentially feature in the campaign. The general population doesn't know monsters and magic exist, or if they do, they basically pretend they don't exist. Most player characters do not start out as peasants -- they're scholars, explorers, adventurers, etc., but prior to the first adventure, they've probably had little-to-no exposure to the world of monsters and the supernatural. Adventures are likely to involve some sort of paranormal investigation that culminates in a dramatic confrontation with a monster or adversary, typically in its lair. The time that passes between adventures could be anywhere from weeks to years, and there's a system you can use for semi-randomly finding out what developments occur in each character's "normal" life during that time (this is where age and wealth level become relevant).
The page labeled "Character Autopsy" (p152/159) gives a great overview of the (somewhat tragic) trajectory that a monster hunting PC's life is likely to take: Once they get exposed to the supernatural, they find it harder and harder to re-assimilate back into normal life. They keep getting drawn back into the fight against evil, and they kind of end up living two lives: one as a monster slayer (during the actual adventures) and one as a normal person (which can be played out in summary using the "between adventures" mechanics). Eventually, their monster-hunting life may take a toll on their normal human life. If they find themselves unable to maintain normal human relationships, it will be difficult for them to hold on to their humanity over time. I like that there's this risk here where it's not just that the character might die, but that they might end up leading a grim, tragic life if they're not careful to hold onto their relationships or their connection to the "normal" human world. This page promises more information about character arcs in a second book titled "The Hanging Judge's Guide to Transylvania." It's looking like that book probably won't get finished, but I would be very interested to see this content if the author ever posts it somewhere.
The chapter on "Mysteries, Research, and Investigation" (p169/176) lays out a procedure for running the investigation phase of an adventure. There are some basic actions that a PC can do each day, like research a topic, interview witnesses, search a location for evidence, etc. There are some simple mechanics and random tables you can use to determine the outcome of each of these actions. Each day, after the PCs have taken their actions, there's a chance there might be some sort of event, like the adversary killing another victim. This is sort of like the typical rules for D&D combat, where each player gets a turn to act, and then the bad guys get a turn to act, and then you repeat. But instead of rounds of combat that take approximately 6-to-10 seconds, you have rounds of investigation that take approximately 1 day. Once the characters figure out where the adversary is located, they can go there and try to confront them. Even if you're not running the rules exactly as written, this basic procedure is pretty cool, and you might want to adapt it for your game.
After that, there's a chapter on "In-Between Adventures" (p201/208), which is also great. First you roll to see how much time passes before your next adventure -- this could be anywhere from a week to a decade. Then you roll to see if anything bad happens to you as a consequence of your involvement in monster hunting -- one of your relationships might be threatened, or you might suffer from traumatic flashbacks, etc. Then you can choose from a couple different general categories of ways that you can spend your time between adventuring, and you roll to see what the result of that is. The system here is a little like the game of Life -- you can find your true love, get married, have kids, buy a house, get richer or poorer, etc. Some people might prefer not to have the PCs' life events randomly determined like this, but if you're up for it, then I think it could be very interesting. I'm the type of person who likes to show up to a D&D session to find out what happens rather than have the story all written out and predetermined beforehand, so for me, it's pretty interesting that you could show up to play and then find out all these random life events that happen to your character.
Finally, there's a chapter full of handy random tables you can use to create adventures (p227/234). These are always nice to have in a campaign setting.
There's a lot of other stuff in this book too, but the sections I talked about here are the reason why I recommend buying the book. Even if you don't use any of the actual rules, most of my favorite ideas here are system-neutral and could be run using any rules system.
I just want to say to the author: Well done! This is a very cool book! I would love to see that additional information on character arcs (mentioned on the "Character Autopsy" page) if you ever decide to post it.