I'll be honest, I am kind of disappointed by a good bit of this book.
Firstly, you would expect a book that was made by 9 people, to at the very least not have as many grammer problems, missing words, and typos that this book has. Regarding the subclasses themselves, most of them are fine, but a few of them such as the Atonement Monk and the Sacred Kin at first glance seem WAY too powerful, while some other ones such as the Dragoon, College of Keys, and the Spirit Lord (for most of the game for this one atleast, later levels it might be on par if not exceeding the other subclasses) seem fairly weak. Then you have the Entropy Domain, which I think is fine as it is, considering it is a specialist class, but the mechanics and lore don't seem to work too well together. Why does Entropy give you advantage on Death saves? Why does Entropy work to cancel out spells, isn't that more of decreasing entropy? Even just ignoring the word Entropy and replacing it with a more fitting word, let's say....Control, because I can't think of something better. Why does this Anti-mage cleric not have counterspell? Why does it have Blight, or Inflict Wounds? The Lore of this subclass calls it one thing but it's mechanics say it's something completly different.
So, now let's talk about the Backgrounds, their all fine. Fairly common ideas in a backstory I would say, and backgrounds should be that way, otherwise they wouldn't be used often and have little reason to be there. Feature wise their all fine, eyeing over the proficiencies and traits, their fine. It's a background, it's not easy to mess up a background.
The race though, I like the idea. I saw the race and wondered why it doesn't already exist. However I looked over the race and was kind of disappointed. Fey Ancestry and Fey Resistance seem to be pretty counter productive, doing the same thing, quite literally giving advantage on being charmed twice. The Fey Charm doesn't say what the DC for the save is, I would presume Charisma though, and it doesn't give a duration, therefore lasting forever. Regarding the subclasses, level 6 is a very strange time to get something when most other classes get something at 5. The same thing goes for three but since the Aasimar get something at 3 and this is pretty much a Fey Aasimar, I'm okay with that one.
The DM tools were all very nice, the crit tables, the lingering injury tables. All the tables were very nice, Suspicion was okay. I liked the items, but the rarities for a few seem a little off, such as Armor of Ease and the Chaos gear.
I'll be honest, I haven't read the adventure yet but from the reviews I've seen, people like them so that's good.
Lastly the notes were nice, on par with Xanathar's Guide I would say.
If you want this book go ahead and pick it up, the DMs tools are good, the adventure is being liked by the other reviews, the race is a good concept that you could probably use to homebrew a better version. Most of the classes are okay. For $20 it's an okay deal.