The updates for the older maps include the use of the new progression system, the ability for Agent 47 to hide in voilage and better blend in with crowds, a picture-in-picture mode, the "strategic use of mirrors," better combat AI, and other new gameplay features like the use of the briefcase, dart gun, flash grenades, and more. These also include the ability to use the new difficulty levels.
The best part? The HITMAN Legacy Pack will be free to those that own the first game.