Although it has moments of fun, the writing is poor. It's a 700-page book, that feels like it's droning on and on, and then resolves major problems in 1.5 pages. There is not enough descriptive language for major plot points.
The dialogue and plot for characters that are 500 years old feels weak, like in book 2 why would you hide a city for millennia and give it up for a human girl you just met? I feel like the author constantly tells us this character is known for their strength but never gives us enough description of their battles to make that choice ourselves. We never get details of why Nesta is a raging B... and just have to accept it. The author will lazily bring a character back for two moments of plot to miraculously save the whole war and then kill him.
I don't know how this book series got pushed up to the level it has as it's mediocre at best.