This is an endgame book. It deals with the final phase of a chess game, the one that comes after the opening and the middlegame. But it doesn't take the point of view that the endgame is separate from the other two phases. Rather it argues that the game is an organic whole, and that everything is related, at least up to a point. What happens earlier can explain what happens later.
The book also recognizes that the endgame tends to have special characteristics. As much as possible, the author tries to bring out those characteristics so that the reader can come away with basics and underlying principles to help find his or her way through the final phases of their own games.
In Endgame Workshop the author explores subjects that are typically covered in most endgame treatments, but does it differently.
To be sure, he follows the format usually employed in his own lessons, treating ideas across the board as they seem to apply. To be sure, he offers most of the standard stuff, from basic mates, to the opposition, critical squares, and many of the standard techniques used to advance and promote pawns, as well as the defensive weapons to fight against such enterprise.
Pandolfini looks at chess positions, the stuff the game is made of, with less regard to simplicity and more to aptness and circumstances. By playing through the book, however, one should come away with a full array of tactical and strategic weapons to improve their overall endgame play.