This book is surprisingly good.
The LitRPG elements are handled well enough and are interestingly designed. They synergize well with the combat scenes, which are also well written.
The world design(s) are a bit generic, but the second world has some entertaining elements that don’t change things a great deal, but that do have a few interesting effects.
But the real strength of the book is its characters. None of the main characters is exactly what one might expect from a typical LitRPG, and the primary protagonists are fascinatingly drawn. They both have elements of both hero and villain and the reader is left to decide how to categorize both. The primary focus of this book is Ryun, who has been severely psychologically damaged by events revealed in flashbacks throughout the book. (I generally dislike flashbacks, but the way they are used here is quite deft.)
A note on the narrator, who is generallly quite good: His pronunciation of “Anrosh” is indistinguishable from “onrush”, which I found distracting. His pronunciation of the principle protagonist as if it were Japanese, which might be correct given the spelling. (It’s also possible that the name is just an idiosyncratic spelling of “Ryan”;) I hope this pronunciation was that intended by the author.
This book is highly recommended, and if the following books can sustain this level, this will become a new favorite LitRPG series.