Itachi was the perfect shinobi, just like the second Hokage. He was extremely skilled in the basics of ninja arts to the point where he was extremely strong, was tactical in combat and chose his battles, did not let his emotions get in the way of his goals, always opted for the fastest and most reliable strategies, and in the end he even chose the way he would die specifically to have the most beneficial outcome to his village.
That does not mean that he was invincible, or that he couldn't be beaten, or that he would have even been useful in the final fight against 10-tails rukido madara.
