Blood of Elves is a novel in the world of The Witcher and part of a series. If you are familiar with the games or the Netflix show then the characters will already be familiar. In this regard it's not too easy to judge how the author manages to bring his characters to life as I am already acquainted with them thought the media previously described, this book doesn't seem to deviate in anyway so no real surprises.
The writing is comfortable considering it is translated from Polish and only occasionally stalls the reader with modernism that seem out of place in a fantasy/historic setting. The world of The Witcher is rich in lore and the author conveys information very well thorough without feeling feeling like a lesson or info dump. The plot centers around The Witcher character and his charge Ciri who is destined to become a Witcher, her heritage and apparent other abilities makes her a 'most wanted person' by a number of factions and therein lies the plot.
The book is enjoyable enough I think mainly due to the interesting world they inhabit, the intrigue around who wants Ciri and why, but ultimately this isn't a book you should be reading if you haven't ready the previous books or are not familiar with the storyline from the games etc. My only complaint would be that this feels like a chapter from a larger work (which it is) and doesn't actually have enough happening to feel like it had a 'Beginning, Middle then End' .
In summary: Enjoyable without actually being terribly satisfying.