So, I didn't DNF this because it's a bad book. It's not at all. The magical horses are cool (if somewhat under developed) and a decent fantasy world. I was reading it one night and when I woke up the next morning realized I didn't need to keep reading it. I'm ok not knowing what happens next, or what happens to the characters (though I have some idea of what's going to happen to Jakim). The characters simply didn't draw me in enough, plus it's the first book in a series I don't have any impetus to continue in so finishing the first book isn't that big of a deal.
I will say it's a book that takes time to get into. The prologue and first chapters are overwritten. When you're introducing readers to a fantasy world, with a lot of names and labels for things, it's not a good idea to also make the language heavy. Like you don’t need adjectives for everything in every single sentence. And you long sentences aren't doing you any favors either.
The world building is all telling in labels and foreign words and descriptions of landscapes or clothing. There's no depth, no history or substance to it. Which is fine for a lot of books but this one felt dense, like it wanted to be more but wasn't quite pulling it off. Slowing the action down some to develop the characters and integrate the world building into the character's experiences would have gone a long way to keep me reading.
Also, I can't help it, the prologue wreaked of The Hero and the Crown by Robin McKinley (which I love) and it wasn't helped by using her labels with the Sol. I know that term doesn't belong to McKinley in any way but when you're talking about extraordinary horses and a scorched landscape and then you have the solborn and Sol-Donair it's too close to the sol and sola of Damar.