Disclaimer: This is from the point of view of someone GMing for the first time. I've played in several Savage Worlds campaigns, and recently decided to try my hand at GMing. I investigated a bunch of different settings material, and Agents of Oblivion (AoO from now on) sounded really promising. Here are my impressions after four sessions (spoiler alert: they aren't positive).
I believe AoO fails in two crucial ways: It violates the Fast! Furious! Fun! ethos of Savage Worlds, and Horror and Espionage don't really mix that well after all. These two elements overlap, as I will attempt to explain.
Firstly, AoO introduces a whole new set of Gear, Spytech/Special Training, and SUDS (Single Use Devices). Gear is cool new equipment, and Spytech/Special Training/SUDs are basically Edges in the form of physical objects. These items are "purchase" using a new currency called Resource Points. There is also the concept of Data Chips, which are a form of upgrade (can give agents skill upgrades or Edges). All of this stuff can be changed out at the beginning of each mission. Sounds cool, right? It sure seems that way, until everyone is sitting at the table, I outline the mission parameters... and the players spend 45 minutes deciding what Gear/Spytech/etc they want to purchase. Not exactly Fast and Furious. I plan to work around this by sending out a mission briefing to all my players a few days beforehand, but I wish I didn't have to.
My second point is that Horror and Espionage don't really mix, despite the "perfect cocktail..." tagline of this book. To my mind, Horror is about facing things you aren't physically, mentally and/or emotionally equipped to handle. AoO, as you can see from the previous paragraph, is all about the equipping the players. A Novice agent, with their starting free skill points in Fighting/Shooting/Notice/Tradecraft, Agency Branch bonuses and Resource Point equipment purchases, looks more like a typical Seasoned character.
On top of that, AoO uses the "no power points" rule variant for powers. This eliminates most of the Power Edges (since they affect power points), and makes powers and power-focused characters kind of, well, over-powered. One of my players spent most of one session casting Fear over and over and over. I spend most of that session un-shaking my mooks, while they were easily picked off one by one by the other players. Sure, I can create enemies with high Spirit or immunity to Fear or an inexplicable desire to stay more than a large burst template's distance away from one another, but that means I'm spending more of my effort working around something that was already taken care of very nicely in the base ruleset.
This brings us to a phrase you'll come across many times, "The Director has final approval ..." Basically, the authors of this setting let the GM pick and choose what elements to allow or not. I've chosen not to allow anything too science-fictiony, such as data brain chips, anti-gravity devices, and the like. Honestly, though, if you tried to remove enough to make this a real horror setting you'd be removing pretty much all the cool Espionage stuff, rendering the entire first half of this book useless.
The second half of the book is for the GM (the Director, in AoO parlance). This section is both better and worse than the player section. The first 10 pages or so is a mish-mash of contradictory "secret history of the world" conspiracy nonsense. Then there's a couple pages where they talk about creating suspense and horror by limiting resouces (again, forcing the GM to work against everything given to the players in the first half of the book). There's a few more pages devoted to vague talk about the level of aliens, conspiracy, occult, horror and technology elements in your campaign. There's not much concrete, useful information there. Then another 20 pages of synopsis of various secret societies around the globe, many of which are drawn from the real world.
Finally, we get to what is arguably the only really valuable part of this book, the Mission Generator. This is 33 pages of tables you can roll against to come up with missions, plots, goals, enemies, allies, and wonderful new creatures of all sorts. I've used this to generate two missions so far, which my players enjoyed quite a bit. It gives you all the pieces, then it's up to you to connect the dots and figure out how it's all going to fit together. For example: The first mission I rolled up said the enemy organization was the diabloist group Astrum Arentum. The Main Enemy was a Mystic Ally, which meant I had to roll on the Ally table and add some Powers. I rolled a Priest. The Plot Type was Sacrifice, the Goal was Anarchy, the Target was a Corrupted Ally (Private Detective, this time), and the Ally was a Scientist, and the Complication was a Creature (a giant Dinosauroid). Put this all together, and I came up with a mission to rescue a Private Detective, who had been hired by the Scientist to investigate mysterious goings-on in the building next to his lab. The detective had become brainwashed by the group, and was unknowingly going to be sacrificed to help summon a demon to weak havoc in the city. Due to the player's interruption of the ceremony, and its close proximity to the Scientist's lab, the Evil Priest ended up summoning a T-Rex instead of a demon, and the whole thing turned into a three-way brawl in a warehouse between the Agents, the cultists, and an enraged T-Rex. Good times.
The rest of the book is devoted to detailing some sample missions/campaigns, along with a bunch of character templates (some generic, and some specific to the sample missions). The generic templates are useful, especially since they correspond to the entries on the Ally table in the Mission Generator.
So, there you have it. 33 useful pages out of 218, definitely not worth the price of entry. Maybe some of my complaints have more to do with my inexperience as a GM than any flaws in this book, but even my players have been complaining about the time-killing equipment picks and the unbalanced nature of the powers. The player I mentioned previously, who went on a Fear-casting rampage, actually volunteered to re-spec his character to be less broken. I'm currently trying to figure out how to salvage this purchase... I think I may end up reverting to pretty much vanilla Savage Worlds, but keep using the Mission Generator. That should make it a lot easier to create some suspense for my players.
I hope you find my thoughts helpful. I'm giving this thing 3/5, despite it sounding more like a 1 or 2, because it is at least well written and laid out. Basically, it's a not-so-great concept that was executed very well.