A fun fantasy adventure.
Many fantasy tales are defined by the world in which they're set and the "rules" that govern it. "Oaths of Life and Death" fits neatly into that category, taking place on a planet similar to post-medieval early-industrial Earth but decidedly different in certain key regards. Among the most noteworthy differences are the "faumen," five distinct tribes of humanoids, each with the physiological characteristics of a particular animal species: birds, cats, cows, fish, and snakes to be specific. Each faumen race can breed with the humans who also inhabit the world, or each other, though the latter is strongly frowned upon and apparently exceedingly rare. For the most part, the faumen races get along, barring conflicts with certain bigoted human factions, but the cat-like Norzen are often reviled by human and faumen alike due to an apparently heinous act committed by one of their kind in the distant past.
As one might expect with a setup like that, brief interactions, prolonged relationships, and varying degrees of conflict between the humans and the faumen races are a central theme of the story and drive much of what happens in it. There are other aspects, such as encounters with literal monsters and brief glimpses into the world's religions, economics, and technologies, but the focus is on societal elements and the war apparently being waged over them.
If that all sounds interesting, you'll likely enjoy the book as the biggest, most common attributes of the story are the parts it does best. Being part one of a three-part series, you're not going to get a complete experience or any real sense of closure but the point where things "end" makes sense, and there's a substantial quantity of progression and completion for the main plot, which I suspect most readers will find satisfying and worthwhile.
There were a few things I didn't love about "Oaths of Life and Death" but there were many more that I enjoyed, and I found it to be a strong effort overall, especially with it being the author's first attempt at a novel.
Bottom line: If you enjoy adventure tales set in fantasy worlds, with a fair but not excessive amount of social commentary, I'd say that "Oaths of Life and Death" is a journey worth taking. 4.25 stars for me, rounded up so as not to underrate it.