Naruto was never A+ material to begin with. Hardly any popular mangas are in terms of plot, character development, etc. That's probably because it'll end up taking forever to draw/scan/write, and the fact that people don't really care for it. Only those who are fluent in Japanese can fully understand the material. Everyone else just wants to see cool action scenes and want to be given fan service. The only semi-popular manga I'd give a good grade is Tokyo Ghoul, but it's manga isn't even that popular. Only it's crappy anime version is. The reason I say that is because it stresses much more mature themes and it does a great job portraying the emotions of characters, their interactions, and the changes of Kaneki. I'm currently reading Tokyo Ghoul Re and I've already found more satisfaction from it than the entire fourth war. Naruto fails in most of these aspects for having a main character that is static and being too "family-friendly." I'm pretty sure it also goes through every cliche possible. I'll give Naruto a B for part 1, and Shippuden a hard C for being mediocre. The Kaguya arc gets a D-. Still better than an F.