I haven't seen the novel or the manga, only the anime, but so far I've been quite fascinated by it. Both the construction of the story and the development of the characters are very well done, the animation is also very good, especially in the action scenes. However, I see that it has some details regarding the development of Rudeus as a protagonist that does not completely convince me.
But, as an active user on social networks, it is clear that I spoil many parts of the story that have not yet been animated and that are very popular in the novel. These Spoilers cause me intrigue as well as a somewhat more general idea of what the anime itself is about, which makes me see how great the work is, in general.