Goodness, this was a read.
I started this series with the notion that it would similar, yet slightly different than Estes' previous work "Fatemarked". However, that mindset was a disservice to the series, and to Estes himself. Nevertheless my review of this series is in contrast to Fatemarked, as I feel that is fair considering the two take place in the same world/universe.
Let me start off by saying that the evolution Estes has underwent in-between the two series is outstanding. Both Fatemarked, and Kingfall are written in the easily digestible manner that Estes has become synonymous with in my mind. The way he organically builds the world, and it's characters without dumping huge blocks of exposition on you *cough* Brandon Sanderson does this, but his fanatical zealots refuse to admit it *cough*. Kingfall is no different.
I will say that is where Kingfall slightly beats out Fatemarked. The amount of detail of the world, and it's people is higher in Kingfall. At the end of book 1, I could easily visualize everything. Fatemarked has this trait as well, but this series is of a higher degree.
That is also to it's detriment. Each installment in the Kingfall series is MASSIVE, and crammed full of detail, and events that transpire. Having binge read the first 4 books I felt a sense of burn-out with my brain categorizing everything, and keeping track. So much so that I took a short break between books 4, and 5 with a slower reading pace for book 5. In my opinion the previous Fatemarked series was a "less strenuous" read, but in no way of lower quality.
The next thing I will speak on is the characters. I feel like both series has phenomenal characters, with each of them being memorable, and easily distinctive. Another testament to Estes' talent as a writer. The only downside of Kingfall vs Fatemarked being that I felt like Kingfall has just a slight too many POV's. To the point that Estes himself has to break up the narrative in the middle of the series to focus on one set of events, and characters; while putting the others "on the back burner" for a short while. It helps to drive home to you the importance of the events happening in this world, and it's characters, but I think that added to the "burn-out" I experienced, as the story felt very skewed to covering those POV's events over the others.
Lastly I want to touch on what Kingfall did better than Fatemarked undoubtedly. In Fatemarked the main story revolved around the threat of the Deathmarked, and how he was going around sowing chaos by killing the rulers, and heirs of the four kingdoms. The main antagonist being a single individual, whom is later not so much a villain. Only for "at the last second" the real threat presented itself in the form of The Hoard; which lead to the four kingdoms having to unite to stand against them. It felt kind of... abrupt, and worked well for the story, but didn't feel very organic in retrospect.
Kingfall is not at all the same, and handles the main threat much better. In this series it is the ever growing threat of The Thousands. The slow build being covered through every book in the series in the form of the interlude chapters, until the final epic confrontation between The Thousands, and the people of Kingfall. Not to mention Quill's slow transformation, and rise to power as he learned about his true lineage. In this way we see Estes' growth as a writer in making sure we always, in the back of our mind, know what the stakes are, and what will cause the inevitable tipping point in Kingfall.
Overall, as always, Estes has constructed a truly fantastic series. As an author I strongly believe he is criminally underrated, and needs more fanfare. I'm not saying this simply as a fan, but as a reader in general. Estes has a true gift for building his world, and characters to the point that as a reader you can't help but connect with them. Spread the word to everyone who will listen; Estes is incredible.