Personally, I think it is one of the most underrated and best-made Isekai anime that is worth watching, honestly. Both the protagonist and the story are equally fascinating. Although it has some similarity with many other Isekai anime, the detail that this time it is not a completely invincible "Hero" makes it more interesting than most, and even more so if it is a professional assassin reincarnated in a fantastic and magical world.
Excellent review.