The problem is that Sakura is no longer a 12 years old girl, her growth is allways wishes to get stronger and takes a first step in that direction > goes back to how she was before > repeat.
Writing for 14 years with that weekly schedule must suck, but he never really knew how to write female characters, the best one he was able to write was Tsunade (for which he actually did a very good job). Remember when it was announced Sasuke was now a criminal? Even Ino cried, Ino! Why should she care about Sasuke, she never even talked to him on screen, Her and Sakura never really knew much of Sasuke at all, they just like him because of his look, after 3 years they should have wisened up.
Remember the rivalry between Sakura and Ino? What was it about? Sasuke. Sakura actually told Ino, her first friend and the one that helped boost her confidence, that they wouldn't be able to be friends because both liked Sasuke. Well, it was a child's conflict and they became friends again some years after, but even then they keep their crush on a boy they barelly knew?
Hinata's even the only one that allways respected Naruto, for Sakura Naruto's just the 2nd prize. Kishimoto also gave every female character healing powers, even if their abilities don't seem like they fit those powers, this just seems like an excuse to act as if they were useful while the male characters fight freely, i notice Kubo did the same thing with Orihime in Bleach.
As for the themes i kind of disagree, Part 1 was the story of an underdog and going against what people expect of you, Part 2 is about the child of destiny and bloodline strugles. Even the power levels are through the roof, remember when Kakashi had to rest a week for using the sharingan too much in Zabuza arc? Now everybody with a sharingan has mangekyo too. Remember when Sharingan was really rare? Now we have seen them used in people's arms.
I don't really hold it against Kishi, he has been writing 20 pages a week for 14 years, but i think the quality has been droping since soon after Part II began, and i don't see Sakura's character evolving all that much, expecially now that Sasuke has returned.