This book could have been incredible.

This book was partially set in Annwyn, which could have lead to some amazing lore and world building opportunities that the author just missed completely. Why have such a story set in a complete fantasy world, without exploring how that world works in detail?

It was the perfect opportunity for the author to explore the aftermath of abusive relationships from two different perspectives, while the abuser remained the same person. Instead it seemed like the author had forgotten about the abuse for the most part, only briefly mentioning it three or four times in the whole 672 pages.

Additionally, it did not need to be that long. So many times the events were being recapped mere pages after they had happened. I understand characters needing to know about events they weren't present for, but does the reader need to read a blow by blow account in the form of a conversation with another character? Even worse was when characters were recapping in their own head.

There is also a sex scene (the only one in this book), between Malina and the Assassin which I'm not entirely convinced was consensual, despite being portrayed as such. I am going to without a concrete judgement on that until I read the final book, however, since Midas was originally portrayed as being a saviour until that degraded over time.

There seems to be very much the Holocaust allegory in this book, as well. I'm not going to pass judgement on that, since I don't feel it's my place (as someone who isn't Jewish) to do so.
Some specific examples of things that tipped me off:

There are no doubt other examples that someone more educated than I on this subject would be able to pick up on.

There were two specific examples of confusing lore-breaking choices (or perhaps laziness) that I can think of off the top of my head. These will be explained without major plot spoilers. So for context for anyone that hasn't read the books in this series, this is high fantasy with no links to the real world, medical science in this series is somewhere around "You have a grievous wound, put this salve on it", additionally, there has been no mention of Abrahamic religions, instead preferring what seems to be a matriarchal polytheism of some description.

To the points:

I understand these are both relatively minor points within the story, and most people might not even realise the issues I've noted, however for me I found I had to put the book down, take a break and come back to it the following day.

There were also several examples of formatting and spelling errors in this book, I picked up on 4 in the last 300 or so pages of the book alone and don't doubt for a second that there are many more such errors that I missed.

Worst of all, this book didn't really add a vast amount to the overall narrative and gave the overall impression that what was originally meant to be one book has been spread over two books and so this needed a lot of filler.

Overall, I wouldn't recommend this book. I found it to be such a disappointment in so many ways. It was such a shame when the first three books to this day mean so much to me, having helped me realise and ultimately leave a relationship similar to the one Auren was in with Midas. I will go back to the first three books in the future, but now whenever I recommend the series, I specify that the first three are worth while, the fourth and fifth are just let downs. I will still be reading the next book, as stated, so I'll see how that one goes. Hopefully it gets better.