Yes Naruto has learned much more than he has shown, TO START, before the time skip in the hokages office hallway, Jiraiya gave naruto some advice, when he was excited about learning rasengan. Jiraiya told Naruto to never show all of your abilities because once your enemies know all your abilities your enemies can use them against you. Naruto has stayed with this principle ever since. NOW what Naruto learned during his time away, this is manly interpretations of naruto's past behavior, training time, learning ability when taught correctly, healing abilities, and Jiraiya skills. Their also the interview with the writer that details what Naruto has learned, all j-man's jutsu and 3 of minato's... But I won?t use the interview because I don't know how real they are, because I truly believe Kakashi will teach naruto or give naruto the keys to his father?s jutsu and wishes. And the reason naruto does not know these jutsu yet is because he had to be ready and able to perform them. Like the 4ths space/time jutsu which I feel kakashi won't be able to do this jutsu to its true potential because of his overall low chakra, so he would have to give him the keys.
. But, Naruto has always learned by doing (example rasengan) and learns fast and has stamina greater than any I have seen in the manga. Jiraiya was one of the greatest ninja in the naruto world, it is impossible to have a student that want to learn an having a teacher that is willing to teach, and Naruto did not learn anything.
my observation why naruto does not use his jutsu, is that naruto has had so much success using his basic powers and the nine-tails when he has pushed his body to far or is unwilling to do what had to be done. But what naruto truly learned during the three years away, was chakra control and it began his journey learning to control the fox.