The update builds on the original game, offering a wealth of new multiplayer content, such as the addition of a Deathmatch mode, complete with three new maps: Industrial, Suburbs, and Hollow. Co-op has been expanded with some additional levels, and a multiplayer map editor is also included for those that like to tinker.
The update also brings support for fully dedicated servers and makes several updates and optimisations to the game. Multiplayer Pack 1 may have only just been released, but Ubisoft also plans to release a second pack in July (also for free), introducing a Team Deathmatch mode, together with some of the most popular original Ghost Recon MP modes.
You can get more information on the update over at the game's official website.