He was perfectly ready to kill Naruto. Like he said, though, he spared his life on a whim. You can't honestly compare his blood vendetta with what Itachi did. His vengeance would serve nobody but himself. Itachi, however, wanted Sasuke to kill him, just so Sasuke would be revered as the hero who defeated the "evil" Itachi.
Sasuke can't be called a good person just because he was willing to throw his life away for revenge. That's an extreme amount of bullshit, and hurts everyone who cares about his sorry ass. (Though it'd make those of us who hate him just a bit happier.) Once again, it all boils down to Sasuke being an asshat who didn't choose the right path. Itachi destroyed all traces of Orochimaru and the curse seal inside him and let himself die to Sasuke's hand, passing on his Ameterasu, he wanted Sasuke to begin redeeming himself and protect the Leaf village. Whether Sasuke will bother carrying on his brother's wishes remains to be seen. Personally, I've got no faith in him. Plus, we have Sai now.
let me re-clarify, i never said or meant to say that sasuke is good, he is morally ambigious(read: doesn't care or ponder morality) like how I described itachi before the truth was revealed. All I'm saying is, Sasuke can't take much of the blame because he never had a family to guide him on the "right" path, he obtains friends later on and not before he shapes his mind into killing itachi, which wasn't really his choice.
Yes it was his choice to pursue him, but not his original agenda as his agenda was to impress his father and be on equal grounds with his brother until itachi brainwashed him into other plans. You can't just simply force yourself into another realm of thinking after all of your senses are flooded with mangekyou images, which is a genjutsu and genjutsus are primarily used to distract and distort which makes them vulnerable to be killed or manipulated. Like Sasuke did with Manda or like Itachi did with Sasuke and of course how Jiraiya nearly killed Pein(Pain?) with it.
His character background and his ambigousness in morality make him a good character to drive the plot of the story since his family's history and now what he's done has now affected or was a part of about half or more of the story.
In short if there was no sasuke there'd be no greater depth to the anime than the other's stories which aren't shallow tales either but, sasuke's story complements them and brings them together.
on the other comment mentioned by someone, I think madara wants to control konoha again, Pein fits into it as being god of all lesser countries and madara controls a small part of it.
I'm still confused as to how Kisame wanted to help Itachi, possibly another morally ambigious person(read: has a complicated history), but I highly doubt it.
Oh and another thought, I guess the english dub was right about the cursed seal and Orochimaru link, of course that's not 100% infallible, they should probrably all be gone from those afflicted with it, except the source.
Sasuke can't win ANYTHING without the other person going easy or without some power that was never his since birth 
