Spoiler free, guaranteed! Though before I get too far into talking about this, I will say that it would help for context if you read the Legend books that came before, as well as of course the previous ones in this series and the last two. I haven't read the Winglet short stories so I don't know how much they factor into this.
I always focus on the negative side first, and I have to say that Snowfall as the POV character is A Lot to deal with. Out of the other POV characters in this series so far, I would compare her inner monologue most with Peril. Snowfall, understandably, distrusts other dragons (especially NightWings) and is extremely paranoid about all of them. I really wanted to empathize with her but for the first half or so she was so intensely suspicious and thinking everyone was out to get her, and she bit the head off pretty much every dragon who spoke to her, that it was pretty exhausting being in her POV.
I mentioned before I didn't particularly like where the series was going with its dragon-human relationships. I liked it best in the first series where the humans were seen as intelligent pets or prey, kind of like how humans see certain animals. That's why I recommend reading the Legend books, because Dragonslayer is written from the human perspective and some of the things introduced there come up again in this book. I'm not going to give the book a lower score because it's going in a direction I don't like, but I still am disappointed.
This book had a unique way of keeping the reader updated on events happening on the other continent. I thought it was pretty clever. Also, for those wondering, this book does explain how and why animus magic was lost. I personally think this is a bit of a cop-out from the author and still doesn't solve how OP the magic was.
I think this was the shortest book so far, or it felt that way. My Kindle edition didn't even break 300 pages. This is not necessarily bad, as the story kept my interest and it was neat to fall into a ruler's mind for a change so readers got a sense for how it felt to have all that responsibility and power suddenly dumped on the character. I admit I smiled with some of the things that went on particularly with the IceWing kingdom and am very curious to see the aftermath of all that. The book deals a lot with prejudice and judging based on appearances. I was reminded of a line from the Pocahontas song "Savages": they're different from us, which means they can't be trusted. That attitude was permeated a lot in this book, particularly with Snowfall, though we know from past books that other dragons feel the same way. And we sadly know from our own history how long that attitude can last, and how difficult it is to defeat. But we'll see how this series handles it.
Over all, I would say it's a decent book. It didn't blow me away like the last one and I would have to wait to re-read it because Snowfall is an exhausting POV for a while. If you got irritated with the CONSTANT CAPSLOCK of Peril, be warned that it happens a lot here. But it did hold my interest and there are some satisfying moments in there. I am interested in seeing how they solve the breath of evil problem, but not so anxious that the wait will be torture.