So the class itself is well crafted, and as far as my eye can tell quite balanced. If you're looking for a new class, this might be worth giving a whirl. Because it seems mechanically sound, is well designed, laid out, and has excellent artwork, I'm rating the product 5/5 with a caveat:
I don't like "full" classes. I feel 5e did a wonderful thing in creating classes that can be extended via archetypes. When I read this, I just ask myself why it's not a warlock pact and patron. The class is a bit mechanically full, so at least it isn't questionable as to why it's a class and not an archetype (like some classes on the guild) but I think the class fails narratively. The idea is you're cursed, and you're using that curse to your advantage. Being cursed to me isn't something you train for: you aren't spending centuries of study over books, learning the nuances of your faith, or practicing combat for days upon end. You're just... cursed.
So while I think this class is well made, and lots of people would have fun with it, it's not really MY thing.
[5 of 5 Stars!]