Oh its going to be substantial alright - its a whole side story basically. And for those who are throwing flames because it wasnt a huge city addition, GTA:SA is available for download on Xbox Live so its fine.
From the release info:
Since its launch in April, Grand Theft Auto IV has garnered unprecedented praise and acclaim worldwide. Developed by series creator Rockstar North and set in Liberty City, The Lost and Damned features a new main character and plot that intersects with the storyline of Grand Theft Auto IV; new missions that offer an entirely fresh way to explore Liberty City with new multiplayer modes, weapons and vehicles; and a diverse soundtrack with additional music – all with the incredible production values that are the trademarks of Grand Theft Auto.
The official press release: http://www.videogaming247.com/2008/11/20/rockstar-gta-iv-360-dlc-will-have-new-multiplayer-modes-weapons-and-vehicles-says-press-release/
