I wasn't sure at first, but readers who have read the Riyria Revelations series will recognize this as a very distant prequel to that series. Those who have not read those books can absolutely read this series on its own. It stands alone very well. However, I would recommend reading Riyria first if you have any interest in that. A major aspect of that series was piecing together the past, and this can ruin some of the surprises in that series if you read it first. So, read this second!
I really enjoyed this first book. It was a good introduction to the setting, which is vastly different than that of the series it is a prequel to. The different (and similar) ways of thinking between the Fhrey and the Rhunes (the humans) were fascinating. I got quickly interested in the story of Malcolm and Raithe, but I was most attached to Persephone and Suri.
One thing that slowed me down in the story at first was Arion's perspective. The Fhrey rubbed me the wrong way, and so did Arion, although she was definitely the best of them. It took me out of the story and hurt my motivation initially, but I got more interested in her, too, as I continued on.
I am really looking forward to seeing where things go in future novels, with one fairly iconic character in particular, who I will avoid naming in order to avoid massive spoilers to fans of the author's other books. I don't know what to expect. Despite being a prequel series, this is so far back in history that if the story completely contradicts what is known from the other books, that wouldn't even surprise me. It's easy for history to get distorted over time, and I'm really curious to see if that's going to turn out to be the case.
If you enjoyed the Riyria Revelations, this book is a must. If you are interested in this author and don't know where to start, I would start with those first, and then come to this next.