First of ALL you people fail to understand that Itachi has been given the task to capture Kyuubi, NOT destroy konoha.
Either way, even it is said, itachi would not destroy Konoha.
He will get into Konoha undetected, as last time, then use genjutsu to take info from top ninjas, easy targets like Sakura or Chouji. If he is caught anyway, he can escape or kill them in cold blood as long as he does not get the info.
So, if he can extract info easily with genjutsu without making any chaos, whats the meaning to destroying the village and making more trouble foolishly like nagato???