hmm,
naruto is kinda stupid and not very skilled but he can become pretty well determined about things.
For example when he learned the Rasengan, he trained very har for that, he trained almost continouosly.
he trained even when it hurted like hell. Not many people would do that except for Lee.
Just beacause he is so determined, he can learn jutsus at a pretty short time.
some people say that just because he have kyubis chakra he can beat anyone.
He may have the chakra but what good use is the chakra when you can't use it?
So he still need to learn jutsus, and the chakra doesn't make him learn the jutsus faster.
Naruto will one day become one of the strongest and whoop Itachis ass. Or wait a minute, I think Sasuke kills Itachi.

And another thing is that you don't need to be a genius to be a excellent ninja, and that is provven by lee.