@KagePakkun!:
As much as I hate to sit around bashing Naruto, I agree with this.
lol that made me laugh cause it's true XD Don't get me wrong, I enjoy Naruto and all, but he was tremendously idiotic and loud and annoying early on, but shows growth of character as he matures into the Shippuuden series.
Anyways, back to Luffy:
@CupidKirby:
Oda purposely reflects Luffy as a childish idiot with the attention span of a piece of cheese in order to emphasize how messed up and twisted the world is. He sees many things that we don't, and that's a reason why everyone has come to appreciate and respect it.
I couldn't say it better myself. He's silly and he's childish (and unlike Naruto that doesn't really go away), but he's not hopelessly stupid. He sees things, knows what they mean, and knows what he needs to do, even if they break the "common sense" of the One Piece world. You'll see this in Luffy in quite a few places :)