Overall I'm really happy with the book. As others have mentioned the sheer amount of variety in subclasses is astounding, the spells look great, and the new classes look like a lot of fun.
However, I did notice one very particular edge-case in the Crusader fighter subclass which I feel should perhaps be looked over again. For their 18th level feature, they get the 17th level feature from whatever Cleric domain they chose. The problem is that some Cleric domains gain features at 17th level that either build off of features that the Crusader does not get, or instead gains features that the Crusader will never be able to use.
For example, if a player chooses the Arcana domain, the domain grants one wizard spell each of 6th, 7th, 8th, and 9th level. The Crusader though is set up as a 1/3 caster like an Arcane Trickster, and so will never be able to benefit from this feature because they don't have the spell slots to cast those spells. Likewise, the Order domain Cleric's capstone feature builds off of their 8th level subclass feature, which the Crusader fighter does not receive, and the Peace domain's capstone builds off of their 1st and 6th level abilities, which the Crusader also does not receive.
I want to stress that this is all in all a very minor nitpick, especially given how much other content there is in the book, but I think perhaps a different feature would work better in place of what they are currently given.
That honestly though is my one complaint, and to be honest I'm not really sure if there is a good way to fix it without comepletely changing the feature. I still am very happy with my purchase and do think it was completely worth the money.
[4 of 5 Stars!]