A somewhat accurate graph of Naruto's drop in quality.
Invasion of Konoha was not only part of the Chunnin exam but was really good.
There should be a massive drop after the Tsunade arc, and an even bigger one after the timeskip which makes the series just plain go off the chart's bottom for the entire rest.
With one spike for that guy punching Sasuke.
–- Update From New Post Merge ---
That's basically how I feel. Before the war mistakes were forgivable and the rest was still enjoyable, but that war man. That fucking war.
Naruto was really terrible since the timeskip. Not sure how you missed that it all dissolved into endless forests, villain of the week based plotlines, extremely half-assed flat art, zero tension given kids were suddenly taking out the uber villains every storyline or so, and near complete irrelevance given to most of the interesting side cast.
It's pretty much undeniable that the Kishi who wrote Part 2 was no longer an artist, and just a guy doing a job for money.
He lost control of the plot in the Sasuke Pot arc (a terrible arc as well) and never got back on the horse.
The degradation of the art style into bland nothingness alone is proof of this.