Massively unpopular opinion incoming.
In retrospect, Part 2 was exactly what we were promised from the beginning of Part 1. Naruto was never a Harry Potter scenario where they were going to stay schoolkids for the entire narrative - even by the time of Sasuke Retrieval Arc, they were already beginning to be treated as full fledged ninja. Part 2 was less about team dynamics and ninja techniques because it was part 1's job to establish these things, and thus focus on them more prominently. Instead, the focus was shifted to a grander scale to tell stories about the ninja world and its past, the greater conflicts that the world had experienced, the problems with the ninja system, and more mature themes of pain, death, loss, and reconciliation. The absolute best parts of Part 2 were the flashbacks and world exposition. The relationship between Jiraiya and Nagato, Nagato's reaction to the terrible world he was placed in, Hashirama and Madara and their rivalry and friendship, the Uchiha and Senju coming together to build Konoha, the curse of hatred and will of fire and how they've continued to affect people to this day, etc. Outside of flashbacks we have a lot of scenes of people traveling to other places and countries, with only two arcs taking place in the Land of Fire (Immortal Arc and Invasion of Pain), and each place we visit has its own unique sensibilities and characters.
I want to say Part 2 was less about the individual and more about the world, but that isn't true either. Part 2 had tons of really amazing characters with really unique abilities; Deidara and his celluar clay bombs, Hanzo and his Salamandar motif, Danzo and his crazy mutant Sharingan arm, Torune with bug abilities that put Shino to shame, Gai finally getting his chance to shine after doing nothing in Part 1, Madara and his insane dual meteor moment, and the list goes on and on and on. There was less of a focus on tight knit teams, training arcs, etc. because Part 2 reflected the adult shinobi world, one that focuses on larger issues with higher stakes, and the one that Naruto had to experience if he was going to become the leader of a nation. From an authorial perspective, Kishimoto didn't focus on things like hand seals, being assigned missions by the kage, and learning new techniques because we were in a world where A) The reader is already aware of the more fundamental workings of the ninja world and B) Most of the characters introduced or focused on are shown at their absolute prime.
Is Part 2 perfect? No. The growth of the rest of the Konoha 11 could have remained a piece of the puzzle, and one can argue that the power creep got too intense. Is Part 2 bad? No. It's exactly what was to be expected from the beginning and a great look at the darker, more serious, more developed side of Naruto's world.
