A flat story bordering on 1-dimensional.

In terms of plot, the author has some unique insights and overall seems to be doing well. However, in terms of characterization, the personalities of characters feel very off. The personalities of original-work characters when they were younger can be excused, since the author is only supplementing for what might be missing in the original material, but the personalities of the characters that the author has made feels so bad. Whether it's the arrogant, jealous, and admiring kids or the dumbass, careless, and unprofessional spies, new characters just feel like a tool for face-slapping and showing off.

It's terrible from chapter 1, yet somehow the author managed to produce another 700+ chapters without dropping or axing the novel.