Itachi's Talent

Teacher: The honor is mine. Itachi was the most gifted student I ever had the pleasure to mentor...I've never seen such a remarkable student. We barely had to teach him anything at all.
Fugaku: You exaggerate.
Teacher: No, No.

Sasuke: Itachi...Graduated from the academy in one year...Times have changed...And he's a special case.

Fugaku: Keep this up, and you'll be amazing, just like your brother.

Kakashi: What speed...! I couldn't follow his sign-weaving at all...Furthermore, that he would use the shuriken in his right hand as a decoy to distract me...While launching a suiton attack at my feet. Impressive.

DB II, "Uchiha Itachi: the genius descendent of the Leaf’s elite Uchihas, and the one to bring their downfall. "

DB II, "By the age of seven, he graduated Ninja Academy at the top of his class. By 13, he became the captain of ANBU. It is hard to name all his achievements.
But it is hard to say that just these reflect Itachi's abilties. His true potential can ony be recognized by those in his level.
(Picture of Kakashi)
Kakashi, "That's incredible speed. I couldn't even follow his hand seals with my eyes. Also, to use the kunai in his right hand as bait and then attack my legs with water jutsu..."

DBII, " Itachi, who by the age of eight achieves the Sharingan, awakens this legendary ability, the Mangkeyou, which only a few done in the past."

Takl, Kabuto ""so, what i need is not your preaching" "but your abilities and intel"
"….you were a shinobi of Konoha
you were a member of the renowned uchiha clan by blood,
you had the sharingan that awoke mangekyo..." 
"keeping many secrets you prevented a war…
…you had many jutsus and powers."
"Itachi ...you had many things that made you yourself (/unique)."
"no one is fitter for my edotensei than you."
"my pieces/tools themselves are my own power""

Takl, Hiruzen "…From an early age, Itachi was attentive to the teachings and seals forebears left and no one took notice of"
"he was such an acute child that he took in (things about) shinobis of the past and the origin of the village from them by himself..." 
"Perhaps for that reason, he didnt let the clans binding (/the commitment to his clan) restrain him. "
"he could look ahead, for the shinobis…for the village…
and was always concerned about the future of those(=shinobis and the village). "
"At the age of 7 the boy already had a perspective just like that of hokages…"