Well its spectacular the new drawing jutsu, but doesnt seem too much to me, there has to be something more, like some killing-ink jutsu, storm of sharp pencils jutsu etc.
I liked how naruto listened to shikamaru, he was going to make kage bunshin but he believed in shikamaru and skip the fight to focus on the target, this shows quite a developement of naruto, now he chooses his battles and takes advantage of teamwork. Maybe is just nothing and im seeing a simple action too positively.
Sai has konoha headband so he is from konoha, if not he cant join naruto's team, wich is his goal. There can be many answers to why no1 knows him, maybe he was trained in secret, feared (maybe a jiinchuriki ), protected or something like that, he is to supposed to be the strongest of his age there must be a reason to that and that reason is conected to his secrecy.