What are the advantages and disadvantages of the Kings Indian?

Advantages: Mating attacks on the White King, playing for the full point with the black pieces, a wealth of resources to learn from, hyper modern and still played by some top GM's so theory is advancing.

Disadvantages: Theoretically tough for Black in some lines, heavy theory in some lines, possibly cramped positions in some lines with little chance for active piece play, it's a "burn down the bridges" type of counter attacking scheme more than it is a defense

It is a sharp opening that does not give Black much leeway in terms of making any mistakes in the opening. But it does give Black lots of play and can provide a sharp game. While fairly intuitive Black does have to know quite a few variations as White has many options on how to steer the game.

Advantage: Engines do not play the White side so well.

An advantage is that you can get a great game and completely destroy any d4 opening system (ie Colle, Stonewall attack, Torre, London System) with it.